Introduction: I have had a long-standing interest in sex differences in the brain and the roles of steroid hormones, genes, and markers of immune function in understanding sex differences in psychiatric disorders and their comorbidity with general medicine. I believe that an understanding of these pathways will provide knowledge for the development of novel sex-dependent therapeutic discovery. For >30 years at Harvard, I have been working with colleagues that span Harvard schools and departments and other collaborative institutions that integrate fields of study, methods of analysis, and levels of study from basic to clinical to tackle issues of sex differences in medicine and women's health. Relatively little is known about how sex differences in healthy brain development may or may not deviate in producing pathology and the impact on treatment. Further, clinical decisions based on research are primarily based on data from males that are often inappropriate for females, even for disorders (like depression) in which women predominate. Given the gap between the clinical and scientific importance of studying sex effects in medicine and the relative paucity of studies on these issues, the history of my work has contributed to moving this field forward.