Head Start is not far-reaching enough. Look into the results from the Perry Preschool project or the Abecedarian project.
This is a very interesting website:
http://evidencebasedprograms.org/wordpress/?page_id=11"This site seeks to identify those social interventions shown in rigorous studies to produce sizable, sustained benefits to participants and/or society. The purpose is to enable policymakers and practitioners to readily distinguish the few interventions that are truly backed by rigorous evidence from the many that claim to be, so that they can use such knowledge to improve the lives of the people they serve. Although we support many types of research to develop and identify promising interventions, this site’s discussion is limited to the results of well-conducted randomized controlled trials, consistent with a recent National Academy of Sciences recommendation that evidence of effectiveness generally cannot be considered definitive without ultimate confirmation in such trials."
The problem is not that we have no idea how to improve things. The problem is that we lack the political will and don't want to spend the money.
