To increase environmental health literacy (EHL) and leadership skills in Latino youth in Salinas, CA., we worked from 2012-2015 with 15 members of the CHAMACOS Youth Community Council (YCC), an outreach arm of a longitudinal study of impacts of environmental chemicals on children's health. The YCC program provided hands-on research experiences related to Endocrine Disrupting Chemicals (EDCs) in cosmetics and their possible health effects. We use participatory research principles and Bloom's Taxonomy of Educational Objectives to describe the development of EHC and leadership in the youth co-researchers. Using data from multiple qualitative sources, we explore the youths' engagement in a wide range of research and action processes. Promising outcomes, including perceptions of improved youth self-esteem, EHL, leadership, and career orientation are discussed, as are challenges, such as time constraints and high priority youth concerns not addressed by the study. Implications for other youth-engaged participatory science and leadership programs are presented.