In this case study, two high school teachers, a university researcher, and 10 high school students (ages 16-19 years) were part of an action research group that addressed an issue--smoking on school grounds--identified by a high school population as being problematic. The research was guided by the following research questions: "Within a community of practice, what processes and practices will support mutual engagement in learning?" "What type of partnership will emerge between youth and adults in this community of practice?" and "What are group members' perceptions of the value of cultivating a community of practice?" Data methods and sources included field notes, student and teacher interviews, and document analysis. Using the lenses of communities of practice and youth-adult partnership, outcomes report on how mutual engagement and youth-adult partnership emerged.