An extraordinary number of young children are exposed to trauma that impacts their development and well-being. Early care and education (ECE) programs are uniquely positioned to support children exposed to trauma yet may lack access to resources and professional development to enhance their capacity to deliver trauma-informed care. Using a qualitative multiple case study methodology, this study investigated how five urban ECE programs adopted new trauma-informed practices as a result of participating in a collaborative model for professional learning. This model, called the Breakthrough Series Collaborative, is designed to build both individual and organizational capacity to implement new practices and is supported by theoretical frameworks from organizational and improvement science. The study explored the changes that occurred at the individual, classroom, and organizational levels. Results suggest changes in knowledge and attitudes about trauma, empathy, and teacher empowerment; classroom and practice level shifts including social and emotional teaching and family centered communication; and at the organizational level a more caring and collaborative workplace culture and improved interagency collaboration. The results further suggest that professional development delivered at the organizational level may support the coordinated implementation of new TIC practices by both teachers and administrators building organizational capacity to improve and sustain these practices. (author abstract)