This report documents the decisions of six states to transition from the federally run health insurance marketplace (HealthCare.gov) to a state-run platform. Through a review of state laws and interviews with officials, insurers, consumer advocates, and consumer assisters, researchers assess states' reasons for moving to a state-run platform, risks associated with the transition, and potential long-term benefits for state health reform efforts. These findings inform several considerations for state policymakers who might contemplate a similar transition.