INTRODUCTION: In recent years, the U.S. Veterans Health Administration (VHA) has seen an increasing population of transgender and gender diverse (TGD) veterans accessing care. Approximately 139 per 100,000 VHA users had a gender identity disorder diagnosis documented in 2018 compared to 32.9 per 100,000 in 2013. Despite TGD patients being overrepresented within VHA, TGD veterans may distrust or face unique barriers with various aspects of the VHA, including health services research. Existing VHA health research focused on TGD populations is largely limited to secondary analyses of electronic health record data. Identifying strategies to enhance primary data collection is crucial for more deeply investigating health care challenges experienced by TGD veterans using VHA care. Additionally, describing health topics of importance for TGD veterans is important for making the research agenda more patient-centered. In this study, we offer veterans' recommendations for researchers working with underrepresented populations based on our findings. MATERIALS AND METHODS: From September through October 2019, 30 TGD veterans were recruited through VHA lesbian, gay, bisexual, transgender, and queer/questioning Veteran Care Coordinators (LGBTQ+ VCC) located nationwide. Semi-structured interviews were used to explore barriers and facilitators to research participation, recommendations for improving outreach and engagement, and overall perspectives about priorities in health services research. Transcripts were independently and jointly reviewed and coded by two TGD research analysts, including a veteran using VHA care. Codes were derived inductively. Themes were identified using conventional content analysis. The VA Pittsburgh Healthcare System institutional review board approved this study. RESULTS: Participants cited privacy concerns of being "outed" and potentially having VHA benefits revoked, in addition to a level of distrust in researchers' intentions as barriers to participating in studies. Facilitators for participating included feeling a sense of serving the TGD community and accessibility to study locations, especially VHA-affiliated sites. Suggestions for recruitment included tailored messaging and using other TGD peers or affirming VHA staff (e.g., LGBTQ+ VCCs) for study outreach. Mental health and gender-affirming hormone therapy were the most understudied topics identified by participants. Additionally, participants prioritized the inclusion and study of underrepresented subpopulations, such as transgender women of color, transgender men, and non-binary/gender diverse veterans, in future research. CONCLUSIONS: By harnessing the VHA LGBTQ+ VCC network, this study recruited a national sample of TGD veterans to provide insight on methods for more effectively engaging TGD veterans in research and elicited their suggestions for health services research topics. The findings provide numerous suggestions for medicine and public health that are ripe for future research endeavors. Despite the study's lack of gender, racial, and ethnic diversity, findings highlight the need for engagement and study of underrepresented veteran populations. These suggested areas of focus for research in combination with valuable insight on research participation provide researchers with guidance for developing research agendas and designing recruitment and data collection methods that can facilitate future primary research advancing health services research involving TGD patients. Similarly, VHA and non-VHA researchers conducting research involving other underrepresented populations can also gain insight from these findings.