Indonesia, the world's fourth most populous nation, has been decentralizing its education sector for the past decade. In this context, school-based management is essential for improving the quality of education. A mixed-method, multisite assessment of a project that aimed to improve the management and governance of basic education in Indonesia documented positive impact on school-based management in both public and private schools, including "madrasah" (Islamic schools). The following factors were associated with this impact: (1) the program was explicitly based on government policy; (2) technical assistance was provided rather than funding, and the program was manageable and affordable for local partners; (3) the project strengthened local systems and institutions, building commitment at both provincial and district levels; (4) the program was school based and involved members of the entire school community: principals, teachers, staff, parents, and community members; and (5) training was provided on-site in school clusters, was ongoing, and included mentoring in schools to support implementation (one-off training events rarely result in successful reform). (Contains 3 figures and 5 footnotes.)