Young children and their families benefit from early care and education (ECE) settings implementing high-quality practices that support children's well-being, health, and safety. Activities to support quality are a focal point of federal and state investments, including over $1 billion of the Child Care and Development Fund and nearly $240 million in Head Start Training and Technical Assistance. The Culture of Continuous Learning (CCL) project tested the "Breakthrough Series Collaborative" (BSC), a quality improvement methodology developed by the Institute for Healthcare Improvement. As part of the CCL project, ECE centers participating in the BSC learned new strategies for improving evidence-based practices. Participating centers focused on improving teaching practices associated with children's social and emotional learning (SEL). The purpose of this report is to share findings from the BSC feasibility study in ECE centers. The feasibility study examined how ECE centers (i.e., child care centers and Head Start) participated in BSC quality improvement activities and the extent to which the BSC promoted changes in individual practices and organizational dynamics. Findings from the CCL feasibility study can inform recommendations for implementing and evaluating a BSC at a larger scale by including more ECE centers of different types, and across diverse geographic areas. [This report was prepared with University of Massachusetts Boston, Institute for Early Education Leadership and Innovation and JRA Consulting Ltd. For "Promoting a Culture of Continuous Learning in Early Care and Education Settings: A Summary for ECE Leaders. OPRE Report 2021-207," see ED616364.]