Background; Rates of participation in sport decline when students start university. Despite efforts from Sport England (the leading body of sport in the United Kingdom) to attend to this issue through funding behavioral interventions, a significant lack of uptake in sport remains. One explanation for such limited findings could be the lack of psychological theory used in their development. Purpose; These studies sought to provide formative research that could inform the development of a theory-based behavior change intervention. Method; The Theory of Planned Behavior was used to develop questionnaires identifying the modal salient behavioral, normative, and control beliefs (study 1) and key belief targets (study 2). Reasons and solutions to these beliefs and potentially effective behavior change techniques (BCTs) were gained from four focus groups (study 3). Results; Seventeen modal salient beliefs were identified (e.g. health benefits), five of which proved to be important predictors of intention (e.g. approval of friends) and two of behavior (e.g. time constraints). Twelve BCTs were identified as offering utility (e.g. self-monitoring). Conclusion; The three formative studies here identified key psychological targets and relevant content to be included within an intervention. Using this information in the development of a theory-based behavior change intervention may yield a greater number of students participating in sport.