The story of the national evaluation of the Follow Through program mirrors the difficulties in trying to evaluate a complex social program that changed its community service orientation to a strategy of planned variation of early childhood programs. (Author/MLF)

Because it included only public schools and guaranteed both school survival and staff employment rights, the first year of the Alum Rock demonstration (1972-73), as sponsored by the Office of Economic Opportunity, was not a test of vouchers as defined in theory. The demonstration was known, therefore, as a "transition" voucher model,…