Youth participation is a key piece of positive youth development, and perhaps the most challenging one. In using the term youth participation, we refer to a constellation of activities that empower adolescents to participate in decision making that affects their lives and to take action on issues they care about. Unlike other practices connected to the youth development approach, such as caring relationships or safe environments, youth participation pushes against long-held, culturally specific ideas about adolescence, as well as institutional barriers to youth involvement. And yet there is a growing effort in youth organizations, community development, and schools and other public institutions to include young people in leadership, decision making, social justice and change, and evaluation. These efforts, which for the most part have been overlooked by academic scholarship, deserve careful analysis and support. This volume of New Directions for Youth Development takes a step in that direction by offering an assessment of the field, as well as specific chapters that chronicle efforts to achieve youth participation across a variety of settings and dimensions.