OBJECTIVE: To assess the efficacy of mindfulness-based cognitive therapy delivered onsite during work hours in reducing stress and improving well-being in an interdisciplinary chronic care health care team. STUDY DESIGN: A longitudinal, mixed methods, observational pilot study using a survey created from validated assessment tools to measure effectiveness of training. Surveys were completed before training, and 1 and 15 months after training. Twenty-four professionals in the cystic fibrosis Centers at Cincinnati Children's Hospital and the University of Cincinnati participated in 6 mindfulness-based cognitive therapy training sessions. Sessions incorporated mindfulness, cognitive therapy, and experiential exercises for processing feelings related to stress and burnout. RESULTS: The presurvey and 1-month postsurvey responses revealed statistically significant improvements for empathy, perceived stress, depersonalization, anxiety, perspective taking, resilience, and negative affect. Sustained effects were seen at 15 months for empathy, perspective taking, and depressive symptoms. The 1-month post-training surveys reported a quarter of respondents (25%) practiced skills at least 5 times in between sessions; at 15 months, 35% reported practicing at the same frequency. Participants reported using mindfulness skills for personal stressful events (74%), work-related general stress (65%), patient-related stress (30%), sleep or general relaxation (22%), and wellness (13%). CONCLUSIONS: Group mindfulness-based cognitive therapy training was feasible and effective in decreasing stress for interdisciplinary cystic fibrosis care team members who elected to participate. Further investigation is needed to determine optimal dose of training, durability of perceived benefits, and generalizability to health care professionals working with other chronic disorders.