Few studies have investigated the impact of life coaching on self-regulated behavior and well-being. A limitation of past studies has been their reliance on peer rather than professional coaches. The present randomized controlled study compared peer with professional life coaching over a 10-week period with 63 participants. Results indicated that, compared to peer coachees and controls, coachees of professional coaches were more engaged in the coaching process, had greater goal commitment and progression, and greater well-being in terms of environmental mastery; other facets of well-being did not change. The results suggest that the presence of a supportive person may be a necessary but insufficient condition for enhancing goal striving and highlight the importance of expertise in coaching. Recommendations are made for future research and for using life coaching as a methodology for applied positive psychology.