If segregation is what you fear vouchers are a better source of prevention than public schools:

rivate schools participating in Cleveland and Milwaukee’s school voucher programs are much less segregated than the public schools counterparts, according to two landmark studies released today by the Milton and Rose D. Friedman Foundation and in Ohio The Buckeye Institute for Public Policy Solutions. The studies find that students using the voucher program have a more integrated school experience in private schools, contrary to claims that school vouchers lead to greater segregation.

“The widespread claims that private schools have high segregation levels and vouchers will lead to greater segregation are empirically unsupportable,” said the study’s author, Friedman Foundation Senior Fellow Greg Forster. “In these two cities voucher students attend schools that are less segregated than the public schools. School vouchers have the potential to break down neighborhood racial barriers in a way public schools can’t match,” added Forster.

The full report could be found here.