The purpose of the study was to obtain descriptive information from runners concerning various aspects of their running, leading to the development and validation of a scale to measure Commitment to Running (CR) and to examine changes in state of mind during different segments ofa run. The subjects, 250 male and 65 female runners of varying levels of ability and experience, responded to a questionnaire which requested information regarding demographics, attitudes toward running, mental states during a run, and perceived outcomes of running. A 12-item Commitment to Running Scale was included in the questionnaire, and substantial support for its reliability and concurrent validity was provided. Significant differences were found on a number of variables which were expected to predict CR—specifically, length of run, discomfort experienced when a run is missed, and perceived addiction to running. Regression analysis indicated that perceived addiction, state of mind, and length of run are significant predictors of CR. The findings also support many of the popular notions regarding the concept of “positive addiction” to running and changes in mental state which occur during a run.