Positive affect (PA) is associated with better health across a wide range of physical health outcomes. This review reflects on why the study of PA is an essential component of our understanding of physical health and expands on pathways that connect these two variables. To encourage forward movement in this burgeoning research area, measurement and design issues in the study of PA and health are discussed, as are the connections between PA and a range of different health outcomes. Plausible biological, social, and behavioral pathways that allow for positive feelings to get under the skin and influence physical wellness are detailed and framed in the context of several theoretical models. Finally, new directions for the field and important methodological and interpretative considerations that are essential to moving this important research area forward are explored.