The work presented here is a large-scale evaluation of a theory-driven school reform project in New Zealand, which focuses on improving the educational achievement of Māori students in public secondary schools. The project’s conceptual underpinnings are based on Kaupapa Māori research, culturally responsive teaching, student voice, and relationship-based pedagogy. Data were produced by a research team who conducted a three-year external evaluation of the project in 22 of the 33 schools implementing its professional development initiative. The book shows the extent to which a well-conceptualized and culturally grounded program in culturally responsive pedagogy, supported by a well-conceptualized professional development program, can shift teacher practices and understandings. These shifts lead to a reduction in the achievement disparities of minoritized students, as well as support for the students as culturally located human beings. While the professional development project in this book addresses Māori students’ educational achievement, the study’s findings and messages are applicable far beyond New Zealand, because the educational experiences of Māori people are common to many Indigenous and other minoritized peoples in countries around the world.