PROJECT SUMMARY The proposed study will develop and evaluate a transdiagnostic gender-affirmative CBT-based digital mental health intervention for transgender and nonbinary (TNB) adolescents. TNB adolescents are at profound mental health risk. Compared to cisgender (non-TNB) adolescents, TNB adolescents have a two- to three-fold increased risk for depression, anxiety, and suicidality. Moreover, TNB adolescents experience unique stressors related to their gender minority identities that contribute to the development of psychological distress, including depression and anxiety. Yet very little research has focused on adapting evidence-based interventions that are known to be effective in treating depression and anxiety for TNB adolescents by incorporating minority stress considerations, and none have been developed specifically for mobile delivery. Leveraging technology to deliver culturally tailored, evidence-based mental health interventions to TNB adolescents holds great promise to reduce health disparities and improve mental health outcomes in this health disparity population with documented barriers accessing competent mental health care.