This report collects the results of all available studies using valid empirical methods to compare segregation in public and private schools, both in general and in the context of school voucher programs. Examining the widespread claims that private schools have high segregation levels and vouchers will lead to greater segregation, this report finds that both assertions are empirically unsupportable. The existing empirical research indicates that segregation levels in private schools are not substantially different from those in public schools when examined at the school level; that private schools are actually less segregated than public schools when examined at the classroom level; and that private schools participating in voucher programs in Milwaukee, Cleveland and Washington D.C. are much less segregated than public schools. While these findings are descriptive rather than causal, they are sufficient to show that the claims made by opponents of voucher programs are without any empirical foundation. (Contains 23 endnotes.)