As a scientific discipline, social psychology is only a bit older than one hundred years, with most of the growth occurring during the past five decades (McGarty & Haslam, 1997). By most standards, social psychology is a relatively young science.
In discussing the discipline's history, it should be noted that there are two social psychologies, one in psychology and the other in sociology, with the larger of the two being the psychological branch (Jones, 1998). The central focus of psychological social psychology is how the individual responds to social stimuli, whereas sociological social psychology focuses on larger group or societal variables, such as people’s socioeconomic status, their social roles, and cultural norms (Stryker, 1997). Although there have been calls to merge the two social psychologies into a single field (Backman, 1983)-—and even a joint psychology-sociology doctoral program at the University of Michigan from 1946 to 1967--their different orientations make it doubtful that this will transpire in the foreseeable future. In this historical overview, the psychological branch of the discipline will be highlighted.

Wundt and The Dawning of a Scientific Discipline: 1862-1894

German psychologist Wilhelm Wundt (1832-1921), who is widely regarded as the founder of psychology, had a hand in the early development of what would become social psychology. In 1862, Wundt proposed that there should be two branches of psychology: physiological psychology and social or folk psychology (Völkerpsychologie). Largely due to his influential writings, by 1900 Germany's annual bibliography of the psychological literature listed over 200 articles per year under the heading "social psychology." Despite his influence in shaping social psychology in Europe, Wundt's ideas had little impact on American social scientists because his writings were not translated into English and his conception of psychology as the "science of the mind" was incompatible with the new behaviorist perspective in the United States that emerged during the early years of the 20th century. Underlying behaviorism was a philosophy known as logical positivism, which contended that knowledge should be expressed in terms that could be verified empirically or through direct observation. This new "science of behavior" had little use for Wundt's conception of social psychology. This was especially true for the social psychology developing in psychology in America, but less so for sociological social psychology. Thus, psychological social psychology in America, which would become the intellectual core of the discipline, developed largely outside the realm of Wundtian influence.

The Early Years: 1895–1935

An American psychologist at Indiana University, Norman Triplett, is generally credited with having conducted the first empirical social psychological study. In 1895 Triplett asked the following question: “How does a person’s performance of a task change when other people are present?” The question was prompted by Triplett noticing that a bicycle racer’s speed was faster when he was paced by other cyclists than when he raced alone. Being a racing enthusiast and desiring to learn what caused these different race times, he devised the first social scientific experiment.
In this study, he asked children to quickly wind line on a fishing reel either alone or in the presence of other children performing the same task. As he had predicted, the children wound the line faster when in the presence of other children. Published in 1897, this study is credited with introducing the experimental method into the social sciences. Despite the significance of this study, it took a full generation for researchers to understand the social psychological dynamics underlying Triplett’s findings (see the chapter 10 discussion of social facilitation). Despite this accomplishment, Triplett did nothing to establish social psychology as a distinct subfield of psychology.
Credit for this achievement goes to the first authors of textbooks bearing that title, namely, English psychologist William McDougall and American sociologist Edward Ross, who each published separate texts in 1908. Consistent with the contemporary perspective in psychological social psychology, McDougall considered the individual to be the principal unit of analysis in this new science, while Ross, true to the contemporary sociological social psychology perspective, highlighted groups.
Despite the inauguration of this new subfield within psychology and sociology, social psychology still lacked a distinct identity. How was it different from the other subdisciplines within the two larger disciplines? What were its methods of inquiry? In 1924 a third social psychology text, published by Floyd Allport (older brother of Gordon Allport), went a long way in answering these questions for psychological social psychology. Reading his words today, you can see the emerging perspective that would one day permeate the psychological branch of the field:

I believe that only within the individual can we find the behavior mechanisms and consciousness which are fundamental in the interactions between individuals.... There is no psychology of groups which is not essentially and entirely a psychology of individuals.... Psychology in all its branches is a science of the individual. (Allport, 1924, p. 4)

            Allport's conception of social psychology was proposed eleven years after John Watson ushered in the behaviorist era in American psychology. Allport's brand of social psychology emphasized how the person responds to stimuli in the social environment, with the group merely being one of many such stimuli. Beyond this emerging individualist and behaviorist stamp, Allport further shaped the identity of American social psychology by extolling the virtues of the experimental method in studying such topics as conformity, nonverbal communication, and social facilitation. The pursuit of social psychological knowledge through carefully controlled experimental procedures would increasingly characterize the field in the coming years.
As Allport's conception of social psychology gained American adherents, German social psychology was being shaped by the Gestalt perspective, which rejected both the existing European-inspired notion of a group mind and the American individualist stand that groups were not real in themselves. Instead, Gestalt social psychologists contended that the social environment is made up not only of individuals, but of relations between individuals, and these relationships have important psychological implications. Thus, Gestalt social psychologists promoted an understanding of groups as real social entities, which directly led to the tradition of group processes and group dynamics that still exists today. These two schools of thought within psychological social psychology, one in America and the other in Germany, which were developing independent of one another, would soon be thrust together due to events on the world scene.

The Coming of Age: 1936–1945

During the first three decades of the twentieth century, Allport's conception of social psychology emphasized basic research, with little consideration given to addressing specific social problems or broader issues bearing on reform. However, by the mid-1930s, the discipline was poised for further growth and expansion. The events that had the greatest impact on social psychology at this critical juncture in its history were the Great Depression in the United States and the social and political upheavals in Europe generated by the First and Second World Wars.
Following the stock market crash of 1929, many young psychologists were unable to find or hold jobs. Experiencing firsthand the impact of societal forces, many of them adopted the liberal ideals of the Roosevelt “New Dealers” or the more radical left-wing political views of the socialist and communist parties. In 1936 these social scientists formed an organization dedicated to the scientific study of important social issues and the support for progressive social action (Stagner, 1986). This organization, known as the Society for the Psychological Study of Social Issues (SPSSI), contained many social psychologists who were interested in applying their newly developed theories and political activism to real-world problems. One of the important contributions of SPSSI to social psychology was, and continues to be, the infusion of ethics and values into the discussion of social life. Its immediate impact on social psychology in the 1930s was to infuse a more applied character to research. New areas of research spawned during this decade were intergroup relations, leadership, propaganda, organizational behavior, voting behavior, and consumer behavior. 
In other countries, world events triggered changes that further distinguished American social psychology from its scientific cousins abroad. For example, the communist revolution in Russia at the end of the First World War led to a purging of individualist-oriented research and theorizing, a development that stood in stark contrast to the increasing focus on the individual within American social psychology. In 1936, the Soviet Union's Communist Party forbids the use of psychological tests in various applied settings, which effectively prohibited the study of individual differences. At the same time, the rise of fascism in Germany, Spain, and Italy created a strong anti-intellectual and anti-Semitic atmosphere in these countries. To escape this persecution, a number of Europe’s leading social scientists, such as Fritz Heider, Gustav Ichheiser, Kurt Lewin, and Theodor Adorno, immigrated to America. When the United States entered the war, many social psychologists—both American and European— applied their knowledge of human behavior in a wide variety of wartime programs, including the selection of officers for the Office of Strategic Services (the forerunner of the Central Intelligence Agency) and the undermining of enemy morale (Hoffman, 1992). The constructive work resulting from this collaboration demonstrated the practical usefulness of social psychology.
During this time of global strife, one of the most influential social psychologists was Kurt Lewin, a Jewish refugee from Nazi Germany. Lewin was instrumental in founding SPSSI and served as its president in 1941. He firmly believed that social psychology did not have to make a choice between being either a pure science or an applied science. His oft-repeated maxim, “No research without action, and no action without research” continues to influence social psychologists interested in applying their knowledge to current social problems (Ash, 1992). By the time of his death in 1947 at the age of 57, Lewin had provided many of social psychology’s defining characteristics (Lewin, 1936; Lewin et al., 1939).
With the end of the war, prospects were bright for social psychology in North America. Based on their heightened stature in the scientific community, social psychologists established new research facilities, secured government grants, and, most important, trained graduate students. These future social psychologists were predominantly white, male, and middle class. Many of their mentors were the European scholars who had fled their native countries and then remained in America following the war. Yet, while social psychology was flourishing in this country, the devastating effects of the world war virtually destroyed the discipline overseas. In this postwar period, the United States emerged as the unchallenged world power, and just as it exported its material goods to other countries, it exported its social psychology as well. This brand of social psychology reflected the political ideology of American society and the social problems encountered within its boundaries (Farr, 1996).

Rapid Expansion: 1946–1969

With its infusion of European intellectuals and the recently trained young American social psychologists, the maturing science of social psychology expanded its theoretical and research base. To understand how a civilized society like Germany could fall under the influence of a ruthless demagogue like Adolf Hitler, Theodor Adorno and his colleagues (Adorno et al., 1950) studied the psychological parameters of the authoritarian personality. Some years later, Stanley Milgram (1963) extended this line of research in his now famous obedience experiments, which examined the conditions that make people more likely to obey destructive authority figures. Social psychologists also focused their attention on the influence that the group had on the individual (Asch, 1956) and of the power of persuasive communication (Hovland et al., 1949). Arguably the most significant line of research  and  theorizing  during  this  period  was  Leon  Festinger’s  theory  of  cognitive dissonance (Festinger, 1957). This theory asserted that people’s thoughts and actions were motivated by a desire to maintain cognitive consistency. The simplicity of the theory and its often surprising findings generated interest and enthusiasm both inside and outside of social psychology for many years.
Social psychology's concern with societal prejudice continued to assert itself during the 1950s. For example, the 1954 U.S. Supreme Court decision to end the practice of racially segregated education was partly based on Kenneth Clark and Mamie Phipps Clark’s research indicating that segregation negatively affected the self-concept of Black children. In that same year, Gordon Allport (brother of Floyd Allport) provided a theoretical outline for how desegregation might reduce racial prejudice. What came to be known as the contact hypothesis was a social psychological blueprint for reducing hostility between groups by manipulating situational variables. This perspective toward understanding and "fixing" prejudice better fit the behaviorist social psychology practiced in America than the earlier developed authoritarian personality approach. 
The decade of the 1960s was a time of turmoil in the United States, with the country caught in the grip of political assassinations, urban violence, social protests, and the Vietnam War. People were searching for constructive ways to change society for the better. Following  this  lead,  social  psychologists  devoted  more  research  time  to  such  topics  as aggression, helping, attraction, and love. The groundbreaking research of Elaine Hatfield and Ellen Berscheid (Berscheid & Hatfield, 1969; Hatfield et al., 1966) on interpersonal and romantic attraction, for example, was not only important in widening the scope of social psychological inquiry, but it also generated considerable controversy outside the field. A number of public officials and ordinary citizens thought social scientists should not try to understand the mysteries of romance. Less controversial was the bystander intervention research conducted by Bibb Latané and John Darley (1968), which was inspired by the 1984 murder of Kitty Genovese in New York City.
Despite the wariness of some, during the 1960s the federal government expanded its attempts to cure societal ills with the guidance of social scientists. Within this cultural context, the number of social psychologists rose dramatically. Among these new social scientists were an increasing number of women and, to a lesser degree, minority members. Whole new lines of inquiry into social behavior commenced, with an increasing interest in the interaction of the social situation with personality factors. The multitude and diversity of these lines of research would continue into the following decades (Pion et al., 1996).

Crisis and Reassesesment: 1970–1984

When social psychology first emerged from World War II and embarked on its rapid expansion, one of the pioneers in the field, Theodore Newcomb (1951), expressed concern that expectations were greater than anything that could be delivered in the near future. By the 1970s, when solutions to societal problems were no closer to being solved, and as the usefulness and ethics of experimental research came under increased scrutiny, a “crisis of confidence” emerged (Elms, 1975). When this disappointment and criticism was followed by accusations from women and minorities that past research and theory reflected the biases of a white, male-dominated view of reality, many began to reassess the field’s basic premises.
Fortunately, out of this crisis emerged a more vital and inclusive field of social psychology. More rigorous ethical standards were established, and although experiments remained the method of choice, researchers began conducting more correlational studies, as well as employing other methods. Regarding accusations of racial and gender bias, social psychology began moving toward more responsible positions, but such biases have yet to be eliminated from the discipline (Graham, 1992; Tesser & Bau, 2002).
Another important development during this time period was the importing of ideas from cognitive psychology in explaining social behavior. This “cognitive revolution” (see p. 00) greatly enhanced theory and research in all areas of social psychology, and its impact persists today. Accompanying the social cognitive emphasis was renewed interest in the concept of the self, which previously had been the focus of only sociological social psychologists. However, with the waning influence of behaviorism, psychological social psychologists rediscovered the insights of founding social scientists such as William James, John Dewey, Charles Horton Cooley, and George Herbert Mead. Soon the self became a central concept within psychological social psychology.

An Expanding Global and Interdisciplinary View of Social Psychology: 1985–present

By the 1970s, both European and Latin American social psychological associations had been founded, and in 1995, the Asian Association of Social Psychology was formed. The social psychology that developed overseas placed more emphasis on intergroup and societal variables in explaining social behavior than did its American cousin. In the mid-1980s, this overseas influence began to reshape the discipline, as social psychologists throughout the world actively exchanged ideas and collaborated on multinational studies (Fiske et al., 1998; Vala et al., 1996). Many of the new ideas about social behavior were generated by scholars from collectivist cultures who were raised within societies that have a very different perspective on the relationship between the individual and the group than that within the societies of traditional social psychologists. Subsequent cross-cultural research found that certain social beliefs and behaviors that were previously considered universal were in actuality specific to the socialization practices of individualist cultures. Based on these findings, considerable research attention was devoted to determining which aspects of human behavior are culture specific--due to conditions existing within a particular culture--and which ones are due to human's shared evolutionary heritage. Although social psychology’s “professional center of gravity” still resides in the United States, European and Third World social psychology offers the entire field opportunities to escape what some consider the limitations of this “gravitational pull” to perceive new worlds of social reality (Shinha, 2003; Tam et al., 2003). This multicultural perspective will continue to guide research in the coming years.
Contemporary social psychologists have also continued the legacy of Kurt Lewin and SPSSI by applying their knowledge to a wide arena of everyday life, such as law, health, education, politics, sports, and business (Ellsworth & Mauro, 1998; Kinder, 1998; Salovey et al., 1998). This interest in applying the principles and findings of social psychology is a natural outgrowth of the search for understanding.
Despite the dominance of social cognition in the 1980s, some social psychologists raised concerns about the relative lack of focus on emotions and motives in explaining social thinking. These critics of existing social cognitive theories argued that to think of motives and affect as merely end products in a central processing system was to dehumanize social psychology. In the early 1990s, a number of social psychologists sought to establish a more balanced view by blending the traditional hot and cold perspectives into what some have termed the Warm Look. These revised social-cognitive theories proposed that people employ multiple cognitive strategies based on their current goals, motives, and needs. Theorists typically developed dual-process models, meaning that social thinking and behavior is determined by two different ways of understanding and responding to social stimuli. One mode of information processing—related to the cold perspective legacy--is based on effortful, reflective thinking, in which no action is taken until its potential consequences are properly weighed and evaluated.  The alternative mode of processing information--related to the hot perspective legacy—is based on minimal cognitive effort, in which behavior is impulsively and unintentionally activated by emotions, habits, or biological drives, often below the “radar” of consciousness. Which of the two avenues of information processing people take at any given time is the subject of ongoing research.
This attention to both explicit and implicit cognition has recently prompted social psychologists to explore how neural activity in the brain is associated with various social psychological processes, including self-awareness, self-regulation, attitude formation and change, group interaction, and prejudice. Although the numbers of social psychologists who pursue such research is still relatively small, the knowledge they acquire concerning the biology of social behavior will undoubtedly play a role in reshaping existing theories. Indeed, the U.S. federal government’s National Institute of Mental Health—which has an annual budget of 1.3 billion dollars--has recently given priority to research grants that combine social psychology and neuroscience.
In concluding this historical overview, if the life of a scientific discipline is analogous to a person’s life, then contemporary social psychology is best thought of as a “young adult” in the social sciences. Compared with some of the more established sciences, social psychology is “barely dry behind the ears” and still subject to growing pains (Abrams & Hogg, 2004; Brewer, 2004; Rozin, 2001). Yet it is a discipline where new and innovative ideas are unusually welcome, where new theoretical approaches and scientific methods from other scientific disciplines are regularly incorporated into the study of social thinking and behavior, and where members of the discipline regularly question the social significance of their findings. In this ongoing critical self-assessment, most social psychologists are confident that their still-young science will continue revealing important insights into how we function as social creatures. Some of the milestones of the field are listed in table 1.

Table 1
Some Milestones in the Field of Social Psychology

The Dawning of a New Discipline and Early Years

1862: Wilhelm Wundt proposes that psychology establish human or social sciences (Geisteswissenschaften) to study the higher mental processes involving language, social practices and customs, religion, and art.

1897: Norman Triplett publishes the first scientific study of social behavior, on a topic that was later called social facilitation.

1900: Wundt publishes the first volume of what would become a classic 10-volume set of  Völkerpsychologie (folk or social psychology) which analyzed a wide variety of social thought and behavior.

1908: Psychologist William McDougall and sociologist Edward Ross separately publish social psychology textbooks.

1920: Willy Hellpach founds the first Institute for Social Psychology in Germany. Hitler’s rise to power leads to the institute’s demise in 1933.

1924: Floyd Allport publishes the third social psychology text, clearly identifying the focus for the psychological branch of the discipline and covering many topics that are still studied today.

1925: Edward Bogardus develops the social distance scale to measure attitudes toward ethnic groups. Shortly, Louis Thurstone (1928) and Rensis Likert (1932) further advance attitude scale development.

1934: George Herbert Mead’s book Mind, Self, and Society is published, stressing the interaction between the self and others.

The Coming-of-Age Years

1936: The Society for the Psychological Study of Social Issues is founded. Muzafir Sherif publishes The Psychology of Social Norms, describing research on norm formation.

1939: John Dollard and his colleagues introduce the frustration-aggression hypothesis.

1941–1945: Social psychologists are recruited by the U.S. government for the war effort.

Rapid Expansion Years

1949: Carl Hovland and his colleagues publish their first experiments on attitude change and persuasion.

1950: Theodor Adorno and his colleagues publish The Authoritarian Personality, which examines how extreme prejudice can be shaped by personality conflicts in childhood.

1951: Solomon Asch demonstrates conformity to false majority judgments.

1954: Gordon Allport publishes The Nature of Prejudice, which provides the framework for much of the future research on prejudice. Social psychologists provide key testimony in the U.S. Supreme Court desegregation case, Brown v. Board of Education.

1957: Leon Festinger publishes A Theory of Cognitive Dissonance, emphasizing the need for consistency between cognition and behavior.

1958: Fritz Heider publishes The Psychology of Interpersonal Relations, laying the groundwork for attribution theory.

1963: Stanley Milgram publishes his obedience research, demonstrating under what conditions people are likely to obey destructive authority figures.

1965: The Society of Experimental Social Psychology is founded. Edward Jones and Kenneth Davis publish their ideas on social perception, stimulating attribution and social cognition research.

Rapid Expansion Years

1966: The European Association of Experimental Social Psychology is founded. Elaine (Walster) Hatfield and her colleagues publish the first studies of romantic attraction.

1968: John Darley and Bibb Latané present the bystander intervention model, explaining why people often do not help in emergencies.

Crisis and Reassessment Years

1972: Attribution: Perceiving the Causes of Behavior, written by six influential attribution theorists, is published. Robert Wicklund and Shelley Duval publish Objective Self-Awareness Theory, describing how self-awareness influences cognition and behavior.

1974: The Society for Personality and Social Psychology (SPSP) is founded. Sandra Bem develops the Bem Sex Role Inventory and Janet Spence and Robert Helmreich develop the Personal Attributes Questionnaire, both of which measure gender roles.

1981: Alice Eagly and her colleagues begin conducting meta-analyses of gender comparisons in social behavior, reopening the debate on gender differences.

1984: Susan Fiske and Shelly Taylor publish Social Cognition, summarizing theory and research on the social cognitive perspective in social psychology.

The Expanding Global and Interdisciplinary View Years

1986: Richard Petty and John Cacioppo publish Communication and Persuasion: Central and Peripheral Routes, describing a dual-process model of persuasion.

1989: Jennifer Crocker and Brenda Major publish their Psychological Review article on “Social Stigma and Self-Esteem,” examining how people respond to being the targets of discrimination.

1991: Hazel Markus and Shinobu Kitayama publish their Psychological Review article on how culture shapes the self.

1995: Claude Steele and Joshua Aronson publish “Stereotype Threat and the Intellectual Test Performance of African Americans” in Journal of Personality and Social Psychology, presenting their research on how negative stereotypes can shape intellectual identity and performance.

1996: David Buss and Neal Malamuth publish Sex, Power, Conflict, an edited text offering evolutionary and feminist perspectives on sex and gender interactions. A growing number of social psychologists attempt to integrate these previously divergent perspectives.

(Because the passage of time ultimately determines what events significantly shape a field, I will wait a few years before adding any more milestones to this list.)