Developmental theory historically viewed demanding roles (at home, job) as important developmental contexts. However, adolescents' participation in these roles has fallen. This qualitative research examined role experiences in United States youth development programs. A central question among others was, "How can youth experience internal motivation fulfilling externally imposed role obligations?" We interviewed 73 youth with substantive work roles (e.g., Leader, Reporter, and Teacher) in 13 arts, science-technology, and leadership programs. Youth (51% female) were 14- to 18-years-old and ethnically diverse. We used grounded-theory methods suited to understanding youth's active learning processes in context. Findings illuminated youth's experiences in 4 important transactions or "steps." Youth: (a) accepted roles based on personal goals, (b) encountered difficult challenges similar to adult roles (e.g., conflicting viewpoints, role strain), (c) drew on resources to overcome challenges and fulfill role demands, and (d) learned through these experiences. Across these steps, findings suggested 3 powerful development processes. First, youth experienced multiple sources of internal motivation (e.g., agency within roles, personal and social investment, and "good pressure"), which fostered high engagement in role performance and learning. Second, experiences grappling with and fulfilling difficult role demands helped youth build important competencies for action (e.g., strategic thinking, perseverance). Third, youth's experience of accountability to others served as a powerful driver of responsibility development: Because youth were invested, they took ownership of obligations to others and learned responsive modes of thinking and acting, which they transferred to family, school, and elsewhere. We propose that teens would benefit from more opportunities for role experiences like these.