Mindfulness-based interventions for athletes—including Mindful Sport Performance Enhancement (MSPE)—have demonstrated promising results. While initial studies of MSPE have found improvements in many areas of athlete functioning (e.g. flow, anxiety, sport performance), questions regarding the feasibility, acceptability, and effectiveness of the protocol when implemented in real-world settings remain. The present pilot study was the first in which a college coach was supervised in using the MSPE protocol to learn mindfulness and develop a consistent practice, and later delivered a 6-week MSPE intervention to all 30 athletes on a Division III NCAA women’s lacrosse team. With a 100% completion rate, players rated the program as highly successful, engaged in mindfulness practice outside of weekly sessions, and strongly recommended MSPE training for other athletes; qualitative data also suggested several perceived benefits. After the intervention, participants showed significant improvements in questionnaire measures of sport anxiety, mindfulness, difficulties in emotion regulation, and sport performance satisfaction, with medium to large effect sizes. Furthermore, improvements in sport mindfulness and flow were associated with several dimensions of lacrosse performance. As many universities lack resources to support sport psychology services for athletes, the present study—with its focus on generalizability and feasibility—suggests that MSPE can be delivered by a trained coach to potentially benefit athletes’ well-being and performance satisfaction. Ultimately, this “train-the-trainer” model could create a foundation for sustainable integration of mindfulness and/or mental training in general into college athletic departments. Lay summary: The feasibility and success of a mindfulness intervention with a collegiate women’s lacrosse team, when led by a coach trained in mindfulness rather than a professional clinician, sport psychologist, or mindfulness expert, suggests that this “train-the-trainer” model could promote feasible and sustainable integration of mindfulness programs into university athletic departments. Implications for practice In addition to direct delivery of mindfulness training to athletes, sport psychology professionals may be able to affect positive change by offering train-the-trainer services to coaches instead, potentially contributing to the sustainable, long-term integration of mindfulness into university athletic departments. Following supervised mindfulness training and the establishment of their own continuing mindfulness practice, the results of the present study suggest that collegiate coaches can feasibly deliver a mindfulness intervention to an entire team with a high degree of acceptability and athlete engagement. Having coaches trained in mindfulness could impact student-athlete well-being and performance satisfaction, and may be especially beneficial for secondary school or university-level athletic departments that lack the financial resources to employ a sport psychology professional.