This report presents the results of one of the first empirical investigations of how a tax subsidy for tuition costs actually influences parents' school choices. It provides data about subsidy costs, utilization, and effects in Minnesota, the first state to have a tuition subsidy pass judicial review at all levels of the court system. The study also examines the effects of other state aid policies on nonpublic school operations and on parent choice of school, and it investigates the process by which parents make schooling choices. The study was undertaken to analyze the operation of a tuition tax subsidy within the broader policy context that shapes school choice decisions. The findings suggest that Minnesota's nonpublic school policies may in fact remove some of the obstacles to private school choice, by lowering costs and increasing access for those who might not otherwise be able to choose private schools. However, the tuition tax deduction by itself appears to have little or no effect on parental choice, while it disproportionately benefits parents with higher incomes and educational levels. For those parents at the margin, policies that directly increase access to schooling alternatives (through lower immediate costs and increased convenience) are more likely to affect actual schooling choices than is an indirect tax subsidy.