Many community mobilization activities for youth violence prevention involve the researchers assisting communities in identifying, adapting, and/or tailoring evidence-based programs to fit the community needs, population, and cultural and social contexts. This article describes a slightly different framework in which the collaborative research/evaluation project emerged from the community mobilization activities. As will be discussed, this collaborative, sustained partnership was possible in the context of the Center on Culture, Immigration and Youth Violence Prevention's (UC Berkeley ACE) community mobilization activities that brought the issue of youth violence, particularly among immigrant and minority populations, to the forefront of many of the community partners' agendas. The East Bay Asian Youth Center (EBAYC) was one of the partners that came to the table, which facilitated the community-based engagement/mobilization. UC Berkeley ACE collaborated with EBAYC to evaluate an after-school program and an alternative probation program serving a diverse youth and immigrant population, including African Americans, Asians, and Hispanics. This article describes UC Berkeley ACE's community mobilization activity and the collaborative partnership with EBAYC, discusses how the evaluations incorporated community-based principles in design and practice, and presents some findings from the evaluations.