The Louisiana Scholarship Program (LSP) is a school voucher initiative offering publicly-funded scholarships to students from economically-disadvantaged families to attend participating private schools. Experimental evaluations of the program report large initial negative effects of LSP scholarship usage on standardized assessments after one year that decrease to insignificance by year three and again become negative by year four. Our study explores variation in treatment effects across 14 measures of school quality, school resources, and other school characteristics in the first two years of the program. We find no consistent evidence of mediation that is robust across two analytical sample specifications.