Forensic psychology can be viewed broadly, as the study of all aspects of behavior directly related to the legal process, or more narrowly as a subarea of clinical psychology involving evaluations of, and testimony about, individuals in reference to a legal question. This chapter traces the history of attempts to apply psychological concepts and data to the legal system, beginning with the evolution of the insanity defense in eighteenth‐ and nineteenth‐century England. As the field of psychology emerged at the beginning of the twentieth century, psychologists' early enthusiasm for applying psychological methods and knowledge to legal questions (e.g., Munsterberg and Freud) was not met with ready acceptance by the legal field. By the 1950s, attempts to inject relevant psychological knowledge into legal cases were becoming more widespread, both by means of clinical expert testimony and via
amicus curaie
(friend of the court) briefs. Involvement of research psychologists in the legal system was sporadic until the 1960s, when an increased emphasis on social relevance led many psychologists to focus their research efforts toward the legal system, studying factors such as eyewitness memory, pretrial publicity, civil rights, judicial instructions, and jury decision making. Paralleling this research emphasis was the founding of professional organizations such as the American Psychology‐Law Society in 1969, the initiation of several psychology‐law journals in the last three decades, and the development of training programs focused on forensic psychology; some of these were joint degree (JD/PhD) programs, while others were within existing clinical or social psychology programs. Several emerging roles for psychologists in the legal system are discussed: providing forensic clinical evaluations, delivering scientific expert witness testimony, creating “science translation” briefs, and working as a trial consultant. In recent years, research intended to provide courts with relevant and useful information has been especially prevalent in the areas of eyewitness memory, ways to improve clinical forensic evaluations, and issues involving children and adolescents. We conclude that the future of forensic psychology looks bright, as communication between leaders in law and forensic psychology appears to be increasing in both frequency and understanding.