Background: Effective physical activity (PA) interventions are needed to counter the insufficient and declining levels of PA in youth. These require an updated, comprehensive planning framework that consolidates recent decades of progress in promoting PA in young children, children, and adolescents. Effective PA interventions require program planning and conceptual model development that target a coordinated and multilevel set of age-specific PA determinants. Accordingly, this paper presents a comprehensive planning framework that researchers can use to design intervention research to promote PA in youth. Methods: The first author conducted targeted searches through Google Scholar to compile PA models/frameworks/guides applicable to youth, a comprehensive set of PA determinants, and determinant-linked strategies to promote PA focusing on review articles. The information was summarized in tables, synthesized, and used to create a planning framework, all of which were reviewed by coauthors. Results: The APPLE Framework for Planning PA Opportunities for Youth (APPLE = Age, PA focus, Place and time, Leverage relevant influences and strategies, and ensure Enjoyable PA opportunities) incorporated all core elements from targeted reviews to create a comprehensive planning framework. The APPLE Planning Framework has a set of questions/prompts that guide the intervention planning process and conceptual model templates to organize planning efforts for designing intervention research. Conclusions: The APPLE Framework for Planning PA Opportunities for Youth will enable researchers to develop comprehensive conceptual models to guide the design of PA interventions for youth. Future research should refine the model and its components to enable PA intervention research in youth to move forward.