In recent years, accountable care organizations (ACOs) have become more prevalent in the United States. This study describes the origins, implementation, and early results of Minnesota's Medicaid ACO payment model, the Integrated Health Partnership (IHP) demonstration project. We describe the structure of the program and present preliminary evaluation results to document the state's important work and to provide lessons for other states interested in implementing Medicaid ACOs. The IHP program has expanded in size over time, the state has reported significant savings, and evidence exists of capacity building among participating providers. We identify factors that may have contributed to the program's early success, but more work is needed to investigate the specific drivers of quality improvement and savings within Minnesota's ACO program and to compare the design and effects of the IHP with other Medicaid and Medicare ACO programs. We conclude with comments about the future of the state's Medicaid ACO program and situate Minnesota's findings within the context of the broader ACO movement.