Dalton et al. (2001) described the field of community psychology as focused on the interdependent relationships of individuals to communities and society, committed to generating valid knowledge that is useful to communities, and involved in research and action through collaborative partnerships with individuals and communities. These principles were examined during the implementation of 2 community youth access-to-tobacco interventions. We worked collaboratively with police and school officials to adopt policies directed at lowering rates of tobacco use among youth. While implementing these community-school-university preventive interventions, we learned that prevention programs are more likely to achieve their goals when community members are involved and the program is responsive to the community's needs and resources. These types of programs, which are sensitive to the ecological interdependence of individuals and their communities, are more likely to impact the modification of community norms and values, be sustainable, and ultimately generate new knowledge.