Despite the documented and well-publicized health and well-being benefits of regular physical activity (PA), low rates of participation have persisted among American older adults. Peer-based intervention strategies may be an important component of PA interventions, yet there is inconsistent and overlapping terminology and a lack of clear frameworks to provide a general understanding of what peer-based programs are exactly and what they aim to accomplish in the current gerontological, health promotion literature. Therefore, a group of researchers from the Boston Roybal Center for Active Lifestyle Interventions (RALI) collaborated on this paper with the goals to: (a) propose a typology of peer-based intervention strategies for use in the PA promotion literature and a variety of modifiable design characteristics, (b) situate peer-based strategies within a broader conceptual framework, and (c) provide practice guidelines for designing, implementing, and reporting peer-based PA programs with older adults. We advance clarity and a common terminology and highlight key decision points that offer guidance for researchers and practitioners in using peers in their health promotions efforts, and anticipate that it will facilitate appropriate selection, application, and reporting of relevant approaches in future research and implementation work.