Design of a Lay Health Worker Training Intervention to Promote Mental Health Care Access for Racially Diverse Transgender Youth - PROJECT SUMMARY Transgender youth face a high risk for serious mental health problems (e.g., suicidality, depression, anxiety) relative to cisgender youth due to their disproportionate exposure to transphobic discrimination and trauma, and significant barriers to mental health care. mHealth interventions have been developed to address the needs of transgender youth and their caregivers, but are underutilized. Lay health worker (LHWs) are individuals who use their lived-experience, language and/or culture to support patients and/or families in mental health service access and engagement. In response to PAR-22-109 and NIMH Strategic Objective 4: Strengthen the Public Health Impact of NIMH-Supported Research, we seek to increase mental health care access for transgender youth by enhancing the dissemination of evidence-based mHealth interventions through the design of a gender-affirming training intervention for LHWs, with cultural tailoring for transgender youth of Color and their caregivers. Specifically, we will use human centered design (HCD) to adapt a gender- affirming mental health provider training intervention (developed by MPI Price K23MH124670) based on data from MPI Barnett (R01MH117123-02S1) on the needs of transgender youth of Color and their parents receiving LHW services. The proposed R21 study involves working with community partners (i.e., transgender youth, their parents, and LHWs) to (Aim 1) co-design a mechanism-driven gender-affirming training intervention for LHWs, then (Aim 2) build the gender-affirming LHW training intervention via usability testing. This study will result in an acceptable and refined training intervention ready for testing in a large, multisite R01 study.