This paper presents the results of two complementary studies that aimed to improve understanding of methods for developing self-regulatory skills in sport. The first (Study 1) investigated the effects of levels of expertise on the self-regulation of transgressive behavior in sport. The second (Study 2) examined the effects of peer education interventions on the development of self-regulatory skills. The Study 1 sample comprised 178 athletes at departmental-regional level and 49 high-level athletes. Study 2 comprised 99 students and 6 high-level sports tutors. Study 1 results showed that high-level athletes saw themselves as more able to resist social pressures and disengaged less than their less-experienced counterparts. Study 2 results showed that peer-education-based interventions affected the tutees’ self-regulatory efficiency scores in resisting social pressures and in social efficacy. These studies suggest that self-regulatory skills improve with increased expertise and appropriate interventions.