Although a number of studies have demonstrated the effects of self-talk on sport performance, the research literature on the antecedents of self-talk in competitive sport is sparse. The purpose of this study was to examine both the antecedents and the consequences of self-talk during competitive tennis performance. Eighteen adult tournament players were observed during United States Tennis Association–sanctioned matches. Players’ audible self-talk, observable gestures, and tennis scores were recorded using the Self-Talk and Gestures Rating Scale (Van Raalte, Brewer, Rivera, & Petitpas, 1994b). Results indicated that all players used observable self-talk and gestures during their matches. Furthermore, for all players, match circumstances (e.g., point outcome, serving status) predicted the use of negative self-talk. Positive and instructional self-talk were predicted by match circumstances for some players. The results suggest that match circumstances contribute to the generation of self-talk and provide useful information for researchers interested in better understanding the antecedents of self-talk.