The Adelante intervention, implemented between 2013 and 2018, addressed an important syndemic health disparity for Central American immigrant youth approaching or in high school-the co-occurrence of substance abuse, sex risk (pregnancy, sexually transmitted infections, HIV), and interpersonal violence. Adelante was implemented and evaluated by the Avance Center for the Advancement of Immigrant/Refugee Health, which built on a university-community partnership that has been in place since 2005. Using a tailored, ecological positive youth development (PYD) approach, Adelante employed intervention strategies across ecological levels, including individual, family, peer, and community levels, with the use of social marketing and digital media strategies to link activities under one aspirational identity and support community engagement. Using a Community Based Participatory Research approach with multiple community partners involved in the effort, the research assessed changes in co-occurring behavioral outcomes and tested hypotheses concerning relationships between PYD mediators and these outcomes. Multiple methods were used in collaboration with partners to assess intervention inputs and outcomes-detailed implementation process records; prepost surveys to assess changes in PYD assets, risk behavior knowledge, and prevention skills; a community survey in the intervention and comparison communities (total N = 3,600) at baseline and two follow-up waves; surveys of a high risk cohort (n = 238) at baseline and follow-up; and social marketing campaign surveys (n = 1,549) at baseline with 2 follow-up waves. Analysis showed multiple improvements in PYD mediators and risk behavior outcomes, including an overall 70% increase in knowledge and a 15% increase in prevention skills. Preliminary analysis of risk behavior outcomes demonstrated, for example, a significant, inverse effect on reported sexual activity (past 3 months) for both Adelante intervention community and cohort samples. In addition, self-reported exposure to the social marketing campaign was associated with positive effects on multiple outcomes, including drug use risk and violence attitudes, and improvement in violence/sexual risk behavior outcomes in the intervention versus comparison community. There are few models in the literature that provide a roadmap for how to address multiple, related health conditions in marginalized, immigrant communities, even as most health disparities are associated with complex social ecologies. The Adelante intervention adds a useful model of this nature to the evidence base, and provides support for the ecological approach to PYD with respect to such communities. (PsycInfo Database Record (c) 2022 APA, all rights reserved).