A challenge for current quality improvement efforts in early care and education (ECE) is to produce sustained changes in practices that support positive outcomes for children and families. The field is seeking innovative models that can be tailored for and tested in ECE systems. The Culture of Continuous Learning (CCL) Project will assess the feasibility of implementing a Breakthrough Series Collaborative (BSC) in child care and Head Start settings. The BSC differs from other ECE quality improvement initiatives by building capacity and recognizing leaders across an organization, rather than supporting changes in individual practice through a single coach or consultant. The model promotes change through collaborative teams that include staff (at all levels) and families. A goal is to spread and sustain change in the use of evidence-based practices. The model has supported practice and process improvements in the health, child trauma, and child welfare fields, but has not yet been widely tested in ECE. CCL project staff are in the process of implementing a BSC focused on improvements in practices to support children's social and emotional learning with ECE programs in the Boston area. Programs applied to participate in the year-long BSC and identified core staff (at all levels) to participate in BSC team activities beginning in the summer of 2018. Over the course of the year, BSC team members attend four in-person learning sessions led by social and emotional learning experts and quality improvement specialists. Between each learning session, teams test the practices and processes they identify, primarily using the plan-do-study-act model as they strive to implement, spread, and sustain the improvements across their organization.