Session abstract: According to developmental systems theories, youth drive their own development as they interact with their environments (Lerner, 1998; Ford & Lerner, 1992). How do we study youth experience in a way that highlights their agency interacting in programs, and use this data for program feedback? This session will introduce the Experience Sampling Method (ESM) as an innovative methodology for collecting youth experience data in the moment using smartphone technology (Hektner, Schmidt & Csikszentmihalyi, 2007). With ESM, youth receive mobile notifications to answer brief surveys about their momentary program experiences (e.g. “How engaged are you right now? How connected do you feel to the people around you right now?”). Using an evaluation of a youth civic engagement program, we will explore what evaluation questions can be answered using this method, how to collect this data and map it onto other data sources, as well as advantages and challenges of this method.