Understanding the history of diagnostic classifications, mental health assessments, real-life tests, and reparative treatments is essential to the provision and advancement of genuinely affirmative care. Participants will learn about the foundational theories of gender diversity in Western cultures and the perspectives of the main proponents of various treatment philosophies. The historical role of mental health providers as gatekeepers for medical transition will be critically interrogated. Most importantly, the workshop will explore the legacy of this history as it impacts modern clinical treatment, therapeutic assessment, and contemporary legislative battles.