Revised Abstract Transgender and gender diverse (TGD) youth (ages 15-24), with gender identities differing from their sex assigned at birth, are a growing NIH-designated health disparities population. TGD youth suffer higher rates of suicide than their cisgender counterparts; over half contemplate suicide in their lifetime. These and other health disparities are compounded for TGD youth who are Black or Hispanic and experience both gender- and race-based stigma and minority stress. Black adolescents are also at an increased risk of suicide; attempts increased 73% from 1991 to 2017. Interventions are needed urgently to improve the mental health of TGD youth, particularly TGD youth who are also racial minorities. We propose a transformative, multi-level intervention to advance equity and reduce health disparities for TGD youth through individual, interpersonal, systemic, and community-based changes that increase knowledge and support among providers, youth, and caregivers, thereby reducing suicidality and improving mental health. Provider and family/caregiver support are known to be critical determinants of mental health outcomes for TGD youth, yet no large-scale interventions exist to address these remediable structural and social determinants of health. Our intervention has two components. The first is a provider training and support program. This entails a free online training course for continuing education credit that teaches providers how to support and communicate effectively with TGD patients and a provider network for increasing psychosocial support. The second is an interactive educational digital platform for TGD youth and caregivers. The digital platform provides expert-generated knowledge via educational modules and uses interactive features to promote communication and strengthen relationships between youth and caregivers. We will use a Multiphase Optimization Strategy (MOST) framework to optimize the platform for testing in a hybrid effectiveness-implementation trial with an Immediate Arm (upfront access) and Deferred Arm (access at 6 months). The intervention period for each Arm will last 6 months, followed by an observation period of up to 12 months with continued access. Using validated subscales, we will assess changes in the proportion of individuals reporting suicidal ideation in the prior three months (primary outcome) and in psychological distress and anxiety, caregiver support, and health care empowerment (secondary outcomes), as well as dose effects, heterogeneity of treatment effects across groups, and within- group resilience factors. This innovative, multi-level intervention fulfills a significant unmet need for near-term and sustainable solutions to the health disparities faced by TGD youth and addresses intersecting forms of stigma and inequity to transform mental health outcomes for a highly vulnerable, at-risk youth population.