Colorado is one of a handful of states piloting innovative health care payment and delivery reforms through Medicaid. Under the Accountable Care Collaborative Program, which began enrollment in May 2011, the state Medicaid agency contracts with seven regional organizations to create networks of primary care providers and ensure care coordination for Medicaid enrollees. Providers receive increased payments, and will eventually be eligible for incentives and shared savings and risk agreements. Results from November 2012 show reduced use of acute care, better control of chronic conditions, and lower total costs among enrollees. This case study is one of three in a series on innovations being undertaken by states to improve quality and efficiency in their Medicaid programs.