This introduction to the Special Section of History of Psychology argues for greater attention to psychological research on sex in the decades before the publication of the Kinsey volumes. Drawing on scholarship by Adele Clarke, Donna Haraway and Wade Pickren, this introduction argues for the centrality of the psychological research projects funded by the Committee for Research on Problems of Sex (CRPS), chaired by psychologist Robert Yerkes after 1921. The three individual papers all speak to opposition to the functionalist approach to sex often attributed to Yerkes' CRPS. (PsycINFO Database Record (c) 2012 APA, all rights reserved).