We examine how low-income parents who apply for North Carolina's Opportunity Scholarship program navigate major obstacles to their full participation in this means-tested private school choice program. Using a mixed-methods approach, this study draws upon administrative data from the state agency that oversees the program, surveys of every applicant family across two consecutive school years (2015-16 and 2016-17), and focus group data from two regions of the state. We uncover four major themes related to applicant families' decisions to explicitly or implicitly decline the offer of a private school voucher: Program eligibility requirements, parents' difficulties acquiring program information to assist with the application process, students' inadequate academic preparation, and financial barriers to participation. Even though eligible families can qualify for financial assistance of up to $4,200 per year, hidden costs appear to play a particularly important role in voucher use. We discuss the policy implications of these findings and offer recommendations.