History's mysteries demystified: becoming a psychologist-historian.

More than 40 years ago, psychologist-historian Robert Watson argued that the study of history was of particular salience to psychology. In this article we explore the relationship between psychology and history and argue that the psychologist-historian plays a vital role in the discipline of psychology. We provide a brief overview of the emergence of the history of psychology as a professional subdiscipline, describe who psychologist-historians are, explain why they are needed, and detail how to join their ranks. We argue that increasing historical sophistication among psychologists will have beneficial effects on research and teaching, and we invite all psychologists to participate in the making of psychology's history.