Congress mandated an intensive study of the effectiveness of Head Start, the "Head Start Impact Study", which has issued a series of reports on the design and study of a target population of 5000 3- and 4- year old children. The Head Start Impact Study First Year Findings were released in June of 2005, and the Executive Summary is available from Health and Human Services. The study participants, beginning in fall 2002, were assigned to either the headstart program or other parent-selected community resources. Thus, the study measured Head Start's effectiveness as compared to a variety of other forms of community support and educational intervention, as opposed to comparing Head Start to a non-intervention alternative.
The results of the first report showed consistent small to moderate advantages to children from participating in Head Start programs rather than other programs, with a few areas where no advantage was reported. The benefits improved with early participation and varied among racial and ethnic groups.