Background: Transgender people experience discord between their gender identity and birth sex, defined as gender dysphoria. Gender-affirming treatments (GATs) are medically necessary treatments to reduce gender dysphoria. However, among transgender Veterans (trans Vets) who desire GATs, not much is known about barriers and facilitators to accessing and receiving GATs in VA and VA Community Care (CC). To ensure effective and equitable GAT access for trans Vets, it is critical to understand: [1] GATs trans Vets receive and where they receive them, [2] barriers, including social determinants of health (SDOH) barriers that are highly prevalent among trans Vets, and facilitators associated with desired GAT receipt in VA and CC, [3] how barriers and facilitators influence GAT access and desire, and [4] how to improve GAT access in VA and CC. Significance: This study addresses the 2022 HSR&D priority areas of Access to Care, Health Equity/SDOH, MISSION Act, and research gap of underserved LGBTQ+ Veterans. It is also a high priority for our operational partners in VA LGBTQ+ Health Program, Pharmacy Benefits Management, Office of Integrated Veteran Care, and Office of Mental Health and Suicide Prevention. Knowledge gained from this study will ensure that GAT delivery in the VA is patient-centered and is responsive to the lived realities and needs of trans Vets. Innovation and Impact: This study will be the first to characterize the GATs received in VA and/or CC to understand how VA and CC are balanced in terms of delivering GATs. This study will also provide novel data on trans Vet experiences related to GAT access in CC, which will be likely relevant to other underserved Veterans accessing CC. Further, it will be innovative in providing data on services and resources used by trans Vets to address barriers that influence GAT access. This will be key to developing patient-centered implementation strategies to improve GAT access in VA and CC. Specific Aims: We propose a sequential explanatory mixed method study whose aims are to: Aim 1. Characterize the GATs received by trans Vets in VA and/or CC (VA/CC) Aim 2. Identify barriers and facilitators associated with desired GAT receipt in VA and CC Aim 3: Understand trans Vet experiences related to GAT access in VA and CC. Methodology: Database Aim 1: We will expand our VA cohort of 9,608 trans Vets (IIR 17-238) from 2006-18 to the data available at the time of funding. We will add CC data to determine the types of GATs received by trans Vets in VA and/or CC. Survey Aim 2: We will survey a national sample of trans Vets identified from Aim 1. Among trans Vets who desire GATs, we will determine SDOH barriers, other barriers, and facilitators associated with desired GAT receipt. Among trans Vets who did not desire GATs, we will determine reasons for not wanting GATs. Qualitative Aim 3: From Aim 2 participants, we will recruit a purposive sample of trans Vets who received all desired GAT(s), who received some desire...