People often feel passionate toward activities in sport. But passion can change, and we know very little about how or when passion for sport changes over time. Here, we present a hypothesis about how, when, and why passion changes over time-the seasonal attenuation of passion hypothesis-which predicts that levels of passion toward activities will tend to decline over the course of a season in sport. We tested this hypothesis in three studies with intercollegiate volleyball players (N = 421), intercollegiate athletes from various sports (N = 298), and fans of the Winnipeg Jets (N = 418). In each study, participants reported levels of passion (i.e., harmonious passion, obsessive passion, general passion) at either the start and end of a season (Study 1) or at the start, middle, and end of a season (Studies 2 and 3). Using latent change score modeling (Study 1) and latent growth modeling (Studies 2 and 3), we found that all scores of passion decreased over the course of each season. This has implications for our understanding of how passion changes over time, especially in sporting activities which are often organized in recurring seasons; there appears to be a tendency for a season to sap people's passion over time.