This paper reviews service learning definitions and principles to illustrate common threads connecting service learning philosophy across contexts. Although there is general agreement that service learning occurs in school-based and community-based categories, it cannot be universally defined. Definitions from K-12, higher education, and adult programs generally agree that participants learn and develop through meaningful community service experiences. Ten principles for effective school- or community-based programs, as articulated by the Wingspread organization in 1989, are listed. A matrix is proposed as a tool to plan and facilitate the service learning program regardless of the setting or participants. The matrix includes choosing a definition, stating the setting and the learning goals, describing the experience or activity or community need, preparing for the activity, engaging in the activity, reflecting on the outcomes, and recognizing and celebrating accomplishments. Benefits for participants in service learning activities are summarized. (Contains 14 references.) (SAS)