Recognized challenges in promoting long-term physical activity maintenance may be due to inconsistencies in the conceptualization and operationalization of behavior maintenance terminology in physical activity research. The overall goal of this paper is to propose a framework and agenda for the development of a common set of terms, definitions, and measures for physical activity maintenance concepts that can be widely tested and evaluated. To initiate this effort, this paper (1) provides an overview of conceptual and operational definitions of physical activity maintenance used in the empirical literature; (2) evaluates whether behavior maintenance terms used in addiction science can be translated to physical activity, (3) recommends research directions for developing consensus definitions of physical activity maintenance; and (4) proposes a conceptual model of physical activity maintenance with inflection points that require operational definitions to be decided upon through consensus efforts in the field. Consensus over the conceptualization and operationalization of physical activity maintenance is needed to draw conclusions regarding which policies and programs are best able to promote long-term behavior change.