We have good evidence–from voucher programs in Chile and New Zealand–that large-scale voucher programs will not help the vast majority of poor children and instead will reinforce segregation and inequality. Voucher proponents ignore the complexity of what contributes to student achievement and turn their backs on our goal to build a more democratic society.

http://epsl.asu.edu/epru/point_of_view_essays/cerai-00-37a.htm