This document summarizes key points from the book "Cultures Built to Last: Systemic PLCs at Work" by Richard DuFour and Michael Fullan. The book advocates for professional learning communities (PLCs) as a way to create lasting cultural change across school systems. It discusses how PLCs can be implemented on a large scale through loose-tight leadership that balances autonomy and accountability. The book also emphasizes the importance of ongoing learning, clear direction, and sustained improvement efforts to fully realize the benefits of PLCs over time.