Coaching has become prevalent in early childhood educational settings and has been shown to support teachers’ use of evidence-based practices. However, coaching includes many practices, and it is not known which practices are necessary for affecting change. We developed a model of coaching quality, the Coaching Quality Framework, and a quantitative measure, the Coaching Quality Checklist (CQC). The model and measure were developed to operationalize quality as an aspect of implementation fidelity in coaching interventions. The CQC includes three subscales: Foundational, Supportive, and Change-Oriented. In this study, we used the CQC to code 168 coaching sessions from a randomized control trial of the Pyramid Model. Teacher outcomes were measured using the Teaching Pyramid Observation Tool (TPOT). We found that total CQC scores were significantly correlated with change in preschool teachers’ social-emotional teaching practices, as measured by their overall TPOT scores. The Change-Oriented subscale of the CQC was significantly correlated with growth in TPOT scores, while the other two CQC subscales were not. We also measured the extent to which fidelity to the coaching protocol was correlated with growth in TPOT scores and found it was significantly correlated with growth on two TPOT practices but not overall change in TPOT scores. However, CQC scores were significantly correlated with fidelity scores. We measured how CQC scores varied among coach-teacher dyads and found that 82 % of the variability was attributable to the coach rather than the teacher. The results of this study support the validity of the CQC, indicating it measures coaching behaviors important for supporting changes in social-emotional teaching practices.