This chapter surveys the long and important tradition of law and psychoanalysis in the United States beginning with the work of Oliver Wendell Holmes, Jr., up to the mid-twentieth century. While “tradition” may seem too strong a term for the diverse collection of psychoanalytic writings carried out by legal thinkers over the course of more than a half-century, what ties this work together is a shared recognition of the unconscious depths of the human psyche and the common questions that a psychoanalytic perspective on human behavior raises for law. As this chapter details, many early- to midcentury legal thinkers and judges turned to psychoanalytic ideas for help in addressing a broad set of concerns, including the value of free speech in a democracy, the processes of judicial decision-making, degrees of criminal responsibility, and child custody. The chapter focuses on those legal thinkers in this period whose attention was captured by the unconventional, sometimes even shocking, psychoanalytic ideas about the unconscious, guilt, free will, conflict, instinctual drives, sexuality, and early childhood experience. A study of the psychoanalytic tradition in American law is essential for understanding the vital contribution that contemporary psychoanalysis can make to law today.