Charles Murray argues that early intervention has been oversold:
The take-away from the story of early childhood education is that the very best programs probably do a modest amount of good in the long run, while the early education program that can feasibly be deployed on a national scale, Head Start, has never proved long-term results in half a century of existence. In the most rigorous evaluation ever conducted, Head Start doesn’t show results that persist even until the third grade.
Let me rephrase this more starkly: As of 2013, no one knows how to use government programs to provide large numbers of small children who are not flourishing with what they need. It’s not a matter of money. We just don’t know how.