This chapter begins by deconstructing the definition used for APA recognition of the specialty. It discusses the ways that the specialty of forensic psychology is different from, and similar to, other related professional fields, activities, and identities. This is followed by a brief history of the development of forensic psychology, from its roots in the late nineteenth century to its recognition by APA as a specialty in the early twenty-first century. Finally, it outlines the boundaries of forensic psychology in three ways: its unique knowledge base and skill sets, the problems that it addresses, and the populations that it serves.