Early Head Start is a federally funded community-based program for low-income families with infants and toddlers and for low-income pregnant women. Created in 1995, Early Head Start strives to promote healthy prenatal outcomes for pregnant women, to enhance the development of children ages birth to three, and to promote healthy family functioning. Between ages three and five, low-income children and their families may also be eligible for Head Start, which offers educational, health, nutritional, social, and other services. This brief summarizes findings from number of studies related to Early Head Start and Head Start programs, including the Congressionally mandated Early Head Start Research and Evaluation Project, a rigorous, large-scale, random-assignment evaluation, which concluded that Early Head Start makes a positive difference for children and families in terms of school success, family self-sufficiency, and parental support of child development. (Contains 18 endnotes.)