This article describes positive youth development as a process in which young people's capacity for being motivated by challenge energizes their active engagement in development. The first part of the article discusses the conditions under which this motivation is activated and considers obstacles to its activation in daily life. The second part discusses ways in which caring adults, including mentors, can support this process of positive development. Several frameworks that provide models of how adults can provide needed structure and guidance while supporting youth's development as agents of their own growth are discussed. (Contains 1 footnote.)