Psychological momentum (PM) is often regarded as an important phenomenon that influences athlete performance. Nevertheless, conceptualisations of PM are criticised for being speculative, vague and impractical for scientific inquiry. In contrast, self-regulation is a long-standing, well researched concept used to explain performance outcomes, yet not clearly integrated in current PM conceptualisations. Hence, this thesis explores self-regulation relative to PM. Golf was considered to be an appropriate context for the empirical inquiries on the basis that it serves as a metaphor for managing life’s challenges. Three studies were conducted. The first study entailed a systematic conceptual analysis of PM based on previous conceptualisations and studies in relevant scientific literature. Self-regulatory processes were identified among the key psychological mechanisms and moderators related to PM. The second study aimed to identify key self-regulation strategies in PM experiences among 16 golfers. A mixed method approach including novel “walk-along” and “think aloud” data collection techniques was used. An inductive thematic analysis yielded a comprehensive typology golfing strategies. Nevertheless, the study did not find consistent strategy patterns in positive or negative PM phases. The third study explored the self-regulation of identity (ego-regulation) in relation to PM phases. A staggered multiple-baseline single-case research methodology was used with five golfers (three professionals and two amateurs). Ego-regulation was manipulated through a mindfulness-based schema mode program tailored to golf (Mindfulness for Golf; MFG). Pre-, mid- and post-intervention data showed positive changes among the participants on two dimensions of PM as well as performance outcomes. Overall the results suggest that golfers use idiosyncratic self-regulation processes to facilitate performance, but these are not directly linked to PM phases. Nonetheless, there are promising indications that enhancing ego-regulation through the MFG program facilitates positive momentum among golfers. Based on the results of the studies in this thesis, and for the sake of scientific parsimony and pragmatism, it is recommended that self-regulation models incorporating motivation are used to explain momentum in athletic activity. In this view, PM has the function of describing, not influencing, goal-driven performance