School choice is a highly controversial topic in Massachusetts. It is estimated that a minimum of 200,000 students are participating in some form of school choice in Massachusetts; when considering intra-district school choice, at least one in four Massachusetts students are in a setting over which their families exercised some form of choice. Using data from the Massachusetts Department of Education on district- and school-level enrollment and individual-level data on students participating in inter-district and charter school choice, this study analyzes the impact and policy implications of school choice. Results indicate that school choice is a reality for a substantial proportion of Massachusetts families, though choice opportunities are unevenly distributed across the state. The unmet demand for school choice is widespread. Low-income, minority students are underrepresented in school choice participation. The financial impact of school choice can be substantial, and it is unevenly distributed. In some large districts, tuition reimbursements are especially detrimental, with the losses far exceeding the savings from lower enrollment. Intra-district choice is widespread, though it is very difficult to track. Meeting the mandates of No Child Left Behind (NCLB) for expanded school choice will be challenging. Spaces for intra-district transfers, mandated by NCLB for students in schools that have failed to make Adequate Yearly Progress (AYP) for two years, are quite limited. Massachusetts has successfully developed vocational and special education choice systems that provide students with comprehensive and equitable options. Private and parochial schools in Boston disproportionately serve white students. The report recommends further research on what motivates students and families to enroll in and remain at alternative schools, whether students and parents are satisfied with their choices, and whether choice impacts student achievement. Appended is a listing of the inter-district choice status of Massachusetts school districts for the past two school years. (Contains 12 references.) (SM)