In the United States, students are assigned to public schools based on where they live. School districts have set boundaries and students living in the neighborhoods within those boundaries attend the district's schools. The district's boundaries are further delineated into attendance zones, in which particular homes and neighborhoods are assigned to a particular elementary, middle, and high school. While all school choice policies aim to disrupt this--giving families options other than their assigned neighborhood schools--open enrollment policies specifically target the issue of school and district boundaries by giving families the ability to send their children either to another school within their district of residence (intra-district open enrollment) or to a school in another district (inter-district open enrollment). Today, 47 states and the District of Columbia have open enrollment policies in place giving parents the ability to send their children to public, district-operated schools other than the one to which they are assigned. The goal of this brief is to provide policymakers with an overview of the landscape of open enrollment policies, including how they work, where they operate, and what the research says about their implementation and effect on student achievement. It also offers state policymakers some recommendations to strengthen their states' open enrollment policies. This publication is one of seven in a series of briefs on school choice from the National Comprehensive Center.