Reviewing pre-K research, Grover Whitehurst notes that the “largest impacts have always been associated with children from the most disadvantaged backgrounds,” which he thinks “argues for targeted, intensive programs, not universal ones.” McArdle is on the same page:
I think universality is the enemy of the president’s stated goal, which is to help give poor kids a leg up into the land of opportunity. First, and most obviously, a universal program will be much more expensive than a program targeted to the 20% of kids who are poor (or the somewhat higher percentage whose families have incomes within 1.5 or 2 times the poverty line.) But perhaps even more importantly is the way that the middle class portion of the program will siphon off the best resources, which is to say, the best teachers. Think of the flow of teachers within school districts from poorer to richer schools. The affluent kids are easier to teach: fewer behavior problems, much better preparation for school, and few of them have trouble getting their homework done because the family’s crammed into three rooms with Grandma and Aunt Marie. So the best teachers flow towards the kids who need them least.
There’s no evidence that I’m aware of that pre-school helps middle class kids; it helps poor kids because it makes up for the stuff that middle class parents do (reading readiness, for example), and poor parents can’t or don’t. So if we’re going to pass a big expensive new program aimed at helping poor kids with serious deficiencies in their home environment, I want to target it on those kids, to make sure that they get as much benefit as possible.
The president’s pre-K proposal, which was released this morning, is summarized here. One element of the plan that focuses on the poor:
A state-federal partnership to guarantee pre-K to all 4-year-olds in families at or below 200 percent of the poverty line, to be provided by school districts and other local partners, and to use instructors with the same level of education and training as K-12 instructions.
Earlier debate over universal pre-K here.