Through 134 open-ended online surveys and 28 interviews with school social workers, this qualitative study explored the role of youth development in strengths-based school social work. Youth development activities were defined as opportunities to participate, lead, or contribute. Qualitative data was analyzed inductively using multi-level coding, constant comparison, and other analytical strategies. Social workers facilitated youth development activities through (1) an "integration model" through which they integrated youth development activities into regular tasks within their roles; (2) a "response to a need model" through which they used youth development activities to respond to a school or community need; and (3) a "general resiliency model" through which they used youth development activities to provide protective or promotive processes for students. Social workers facilitated leadership programs, service projects and clubs, weekend retreats, student council, peer leadership and mentoring programs, clubs, and sports. They also referred students to existing programs. Social workers solved problems to ensure that all students, not just privileged students, participated. Positive outcomes of participating in youth development activities included: self confidence, self esteem, sense of identity, sense of belonging, sense of joy, values of citizenship and kindness, social relationships, an increase in the desire to try new things, better behavior, and improved academic performance. Students who participated in youth development activities facilitated by a social worker were also more likely to seek out the social worker for help with personal issues or crises. Key ingredients of successful youth development programs included: encouraging student ownership in activities, building rapport, adapting activities, giving students special jobs and roles, debriefing and processing, teaching skills, and maintaining high expectations. Colleagues and administrators and smaller caseloads supported social workers' ability to facilitate activities. Obstacles included logistical difficulties such as funding and paperwork, overload, not being able to take students out of class, and difficult group dynamics. A model for employing youth development activities as positive behavioral interventions with the general population, at-risk students, and students with identified behavior and emotional difficulties is included. The author also argues for additional curriculum on youth development activities in school social work courses.