‘Head Start’: The $166 Billion Fed Ed Failure. The central result is that at the end of first grade, the HHS detected no benefit, cognitive or behavioral, for the children, nor for the parents.

This does not rule out the possibility of benefits only apparent later. For example, maybe Head Start makes boys less likely to end up in jail as adults. Of course, this is very speculative, hardly justifying the Head Start budget. We have good evidence now that Head Start is a glorified day-care subsidy, so why not slash the budget and voucherize the remainder?

In general, improvements in education are extremely hard to scale up. I wish I had conclusive evidence for a theory of exactly why this is so.