This commentary examines the issue of youth participation in out-of-school time programs from two perspectives. It begins broadly and with a youth-centered lens, by asking how children and youth spend their discretionary time and how time use patterns relate to outcomes. After painting a picture of the full out-of-school time landscape, it looks specifically at structured program participation and provide at least partial answers to some basic questions: Who participates? How much? Why or why not? To close, it draws on the information collected to reflect on policy issues related to participation.