Teachers' stress and training in a school-based mindfulness program: Implementation results from a cluster randomized controlled trial.

School-based mindfulness trainings (SBMT) are a contemporary approach for intervening to promote students' social and emotional skills and well-being. Despite evidence from the larger field of evidence-based social and emotional learning programs demonstrating the importance of high-quality implementation, few studies have investigated factors impacting the implementation of SBMTs, particularly teacher-level influences. The present study addressed this issue by investigating whether teachers' stress, trust in their fellow teachers and principal, and expectations about the program at baseline predicted the quality of their implementation of a SBMT for students. In addition, we examined whether teachers' stress at baseline moderated the effect of training condition on implementation quality. Implementation quality was assessed via observations and teacher self-reports. Results from a sample of British secondary (middle-high) school educators (N = 81) indicated that teachers who felt more supported by their principals at baseline were later observed to implement the SBMT with greater quality, whereas teachers who had more positive expectations about the program felt more confident teaching the course in the future. Teachers' baseline stress moderated the effect of training condition on all measures of implementation quality; among teachers experiencing high stress at baseline, more intensive training led to higher quality implementation. Implications for practitioners and prevention researchers are discussed.