"Head Start" is a national, federally funded program that provides services to promote school readiness for children from birth to age 5 from predominantly low-income families. Based on a review of the research, the WWC found "Head Start" to have potentially positive effects on general reading achievement and no discernible effects on mathematics achievement and social-emotional development for 3- and 4-year-old children. A glossary of terms is provided. Appended are: (1) Research details for DHHS ACF (2010); (2) Outcome measures for each domain; (3) Findings included in the rating for the general reading achievement domain; (4) Findings included in the rating for the mathematics achievement domain; (5) Findings included in the rating for the social-emotional development domain; (6) Description of supplemental findings for the general reading achievement domain; (7) Description of supplemental findings for the mathematics achievement domain; (8) Description of supplemental findings for the social-emotional development domain; (9) Description of supplemental findings for the alphabetics domain; (10) Description of supplemental findings for the cognition domain; (11) Description of supplemental findings for the comprehension domain; and (12) Description of supplemental findings for the language development domain. WWC Rating Criteria and a Glossary of Terms are also included. [The Study that meets WWC group design standards without reservations was: U.S. Department of Health and Human Services, Administration for Children and Families. (2010). Head Start impact study. Final report. Washington, DC: Author. http://files.eric.ed.gov.bibliotheek.ehb.be/fulltext/ED507845.pdf.]