The District of Columbia Opportunity Scholarship Program (OSP) was created by Congress to provide tuition vouchers to low-income parents who want their child to attend a private school. The Scholarships for Opportunity and Results (SOAR) Act of 2011 also mandated an evaluation of the OSP program. This report examines impacts one year after eligible families applied to the program on outcomes such as student achievement, satisfaction with schools, perceptions of school safety, and parent involvement. The program selected students to receive scholarships using a lottery process in 2012, 2013, and 2014, which allows for an experimental design that compared outcomes for a treatment group (995 students selected through the lottery to receive offers of scholarships) and a control group (776 students not selected to receive offers of scholarships). Approximately 30 percent of students offered scholarships did not use them, so the evaluation examines both the impacts of being offered and the impacts of using scholarships. Key findings include: (1) After one year, the OSP had a statistically significant negative impact on the mathematics achievement of students offered or using a scholarship; and (2) The program did not have a statistically significant impact on parents' or students' general satisfaction with the school the child attended in that first year. The following are appended: (1) Lottery Structure, Study Sample, and Impact Findings; (2) Technical Approach; and (3) Additional Analyses.