Family support plays an important role in promoting resilience and health among transgender and/or nonbinary youth (TNBY), but family members often experience barriers to supporting their TNBY, including minority-adjacent stress stemming from exposure to structural stigma and antitransgender legislation. TNBY and their families need effective family-level interventions developed using community-based participatory research (CBPR), which integrates community members (e.g., TNBY, family members, service providers for families with TNBY) into the intervention development process to ensure the resulting intervention is relevant and useful. Informed by findings from the Trans Teen and Family Narratives Project, we used CBPR to develop the Trans Teen and Family Narratives Conversation Toolkit, a family-level intervention designed to educate families about TNBY and facilitate conversations about gender. The toolkit was developed across 1.5 years (June 2019 to January 2021) using four integrated phases: (1) content development: digital storytelling workshop with TNBY; (2) content review: digital storyteller interviews and user focus groups; (3) content development: study team content synthesis and website development; and (4) content review: website review by TNBY, family members, and mental health providers, and intervention refinement. This article outlines the intervention development process, describes strategies employed to navigate challenges encountered along the way, and shares key learnings to inform future CBPR intervention development efforts. (PsycInfo Database Record (c) 2024 APA, all rights reserved).