The aim was to examine how exercise motives differ across stages of change. British government employees completed questionnaires measuring exercise motives and exercise stage of change at baseline (N = 425) and at 3-month follow-up (247 of the original sample). Discriminant analysis was used to determine whether exercise motives (and age and gender) could collectively discriminate between baseline stages of change; and whether exercise motives could discriminate between those who stayed inactive, stayed active, became active or became inactive over the 3 months. Taken as a whole, and with some qualifications, the results suggest that extrinsic (specifically bodily) motives dominate during the early stages of exercise adoption, but that intrinsic (specifically enjoyment) motives are important for progression to and maintenance of actual activity. This is consistent with Deci and Ryan's (1985) self-determination theory. The implications for exercise promotion are discussed.