The adolescent transition is characterized by dramatic biological, cognitive, and social changes that are detrimental for some, but not all, youth. Thus, the aim of our research is to understand “what works when and for whom,” by developing and using increasingly personalized methods to study adolescent behavior. Primarily, students in the interACT lab study how the experience of and progression of puberty can set youth on different cognitive and health paths, but on-going questions also include positive experiences during adolescence, civic engagement, and mental health outcomes. To investigate these questions, we use intensive longitudinal assessments (e.g., daily diary), physiological data collection (e.g., saliva), and behavioral assessments (e.g., neurocognitive testing) alongside secondary data analyses and community-orientated data collection (e.g., youth participatory action research) to better understand youth’s lived experiences.