Abstract
This chapter reviews the history of scientific evidence regarding sexual and gender minority (SGM) mental health, from the unscientific, homophobic theories of the early 20th century to the pioneering research that paved the way for the accurate evidence on SGM mental health that researchers currently possess and continue to acquire. This chapter also discusses historical impediments to creating evidence-based treatments for SGM mental health, including a lack of clear treatment targets and treatment studies specific to SGM, as well as the recent progress toward overcoming these barriers as illustrated in the chapters throughout this handbook. The chapter offers several justifications for the widespread use and dissemination of evidence-based treatments with SGM, including ethical, professional, and scientific considerations in this pursuit. Finally, it provides suggestions for future research to advance evidence-based practice for SGM, spanning psychiatric epidemiology to psychotherapy process research.