Transgender and gender expansive (TGE) youth are at alarmingly high risk for negative mental health outcomes, especially in the current political climate with the surge of anti-trans legislation targeting TGE youth. Research has repeatedly demonstrated that parental support is one of the strongest protective factors that can mitigate these mental health disparities among TGE youth (see Johns et al., 2018). Yet, there are currently minimal evidence-based interventions aimed at increasing parental support for parents and caregivers (PCs) of TGE youth. Dr. Matsuno will present on three studies to demonstrate the process and progression of intervention development and testing. The first study, involves the development and pilot testing of the Parent Support Program (PSP), an online intervention for parents and caregivers of trans and nonbinary youth. The second study is a Randomized Controlled Trial (RCT) of the PSP with PC’s across the U.S. The third study is a pilot hybrid effectiveness-implementation study which tests the effectiveness and implementation of the PCP with PC’s on the waitlist for services at Phoenix Children’s Hospital.