Head Start is a federal program that has provided comprehensive early childhood development services to low-income children and their families since 1965. The comprehensive nature of the program includes educational, health, nutritional, and social services. These services are intended to prepare children to enter kindergarten and to improve the conditions necessary for their success in later school and life. Most children served in Head Start programs are three- and four-year olds, but in 1994 legislation expanded Head Start to include an Early Head Start program, which serves children from birth to three years of age. Except as noted, the term Head Start in this report typically refers to both of these programs. Head Start is administered by the Office of Head Start (OHS) within the Administration for Children and Families (ACF) at the U.S. Department of Health and Human Services (HHS), which provides grants directly from the federal government to local entities (as opposed to providing funding through the state). These entities are called "grantees" and may be public or private agencies, nonprofit or for-profit, faith-based or secular. Currently, roughly 1,600 agencies receive Head Start grants. Head Start strongly emphasizes the involvement of families and the local community to assure that programs are responsive to the unique needs of each community. Flexibility in local program design and operation is encouraged, and there is wide variation across the country in how Head Start services are delivered (e.g., in Head Start centers, through home-based programs, or in some combination), as well as in local program costs, sponsoring agencies, and coordination arrangements with other social service programs. Head Start operates both full- and part-day programs—most (but not all) are only during the school year. Some local Head Start programs do coordinate with other programs to lengthen the time of care, both in terms of hours and the year. Full-day enrollment in Head Start is defined as six or more hours per day. Part-day sessions must comply with a minimum class time requirement of 3.5 hours. The Head Start program is currently due for reauthorization. The Head Start Act was last reauthorized in December 2007, with the enactment of the Improving Head Start for School Readiness Act of 2007 ( P.L. 110-134 ). This law reauthorized Head Start, which had been up for reauthorization since the end of FY2003, through September 30, 2012. The enactment of the 2007 reauthorization law followed unsuccessful reauthorization efforts during the 108 th and 109 th Congresses. A brief discussion of the legislative history related to the 2007 reauthorization (including the efforts of the 108 th and 109 th Congresses) is included in Appendix A . Early Head Start (EHS) was established in the 1994 Head Start reauthorization legislation ( P.L. 103-252 ) to serve infants and toddlers who are generally too young to participate in the regular Head Start program. Up until the passage of the 2007 reauthorization legislation, the law had required that a portion of Head Start's total appropriation be set aside to fund the EHS program. For FY1998, Congress earmarked more than was required by law for EHS, and the statutory set-aside was increased in the 1998 amendments to Head Start. One of the few legislative changes sought by the Clinton Administration during the 1998 debate on Head Start was an increase in the EHS program. The EHS set-asides were 7.5% in FY1999, 8% in FY2000, 9% in FY2001, and 10% in each of FY2002 and FY2003. The 10% set-aside for EHS was maintained up until the passage of the 2007 reauthorization ( P.L. 110-134 ), when the funding allocation structure was changed to fund EHS in a manner that does not involve setting aside a designated percentage. The new allocation formula provides base-level funding for current Early Head Start grantees and allows for additional EHS expansion dollars only if sufficient funding remains following set-asides for training and technical assistance, cost-of-living increases, and expansion funding for American Indian and Alaskan Native (AIAN) Head Start programs and Migrant and Seasonal Head Start (MSHS) programs (more on this can be found in the " Allocation Formula " section of this report). In addition, the 2007 reauthorization law added a provision allowing existing Head Start grantees to convert some of their preschool slots to slots serving infants and toddlers (i.e., children under age three), provided HHS approves a program's written request to do so. The first EHS grants, totaling $47 million, were awarded in September 1995. In FY2012, nearly $1.268 billion was used to support EHS programs across the country. These projects funded enrollment slots for roughly 113,566 low-income families with children under the age of three. EHS grantees must design programs that respond to the strengths and needs of individual families with services including education; home visits, especially for families with newborns and infants; parent education, including parent-child activities; comprehensive health services, including services to women during and after pregnancy; and ongoing parental support through case management and peer groups. All programs must conduct an assessment of community resources and needs and must ensure the recruitment and development of high-quality staff. Head Start is authorized to serve children at any age prior to compulsory school attendance, but most children are three- and four-year-olds (about 83% in FY2012). Pursuant to the program's implementing regulations, Head Start children are generally required to be at least three years old, though certain programs have requested and received authority to serve younger children. By contrast, EHS programs are authorized to serve children under age three and pregnant women. Head Start (and EHS) programs are targeted to low-income children and families. The Head Start Act and accompanying regulations typically require at least 90% of children enrolled by each Head Start grantee to come from families with income at or below the official federal poverty guideline (e.g., $19,530 for a family of three in 2012) and/or to be categorically eligible. Children are categorically eligible if they are (1) from a family that is receiving public assistance (specifically, Temporary Assistance for Needy Families (TANF) or Supplemental Security Income (SSI)), (2) in foster care, or (3) homeless. The statute and regulations further specify that up to 10% of the children served by each grantee may be from families whose incomes exceed the poverty guidelines (and are not categorically eligible). In addition, when Head Start was reauthorized in 2007, programs were given the authority to fill up to 35% of their slots with children from families with income between 100% and 130% of the poverty line, provided that these children are not given higher priority than children who are homeless or living below poverty. In other words, the income eligibility has not been raised to 130% across-the-board, but rather for only a percentage (a maximum of 35%) of available slots and only in cases where priority populations have been served first. Figure 1 shows the percentage of children enrolled in FY2012 by primary type of eligibility. (While some children may meet multiple eligibility criteria, they are reported here only once—by primary eligibility type.) As the figure demonstrates, roughly 3% of children enrolled in Head Start in FY2012 were deemed eligible using the authority to serve families with income between 100% and 130% of poverty. An additional 5% of children were enrolled using the rule allowing 10% of children to be from families whose income exceeds poverty. All remaining children—roughly 93% of all children enrolled in FY2013—were deemed eligible because their family income fell below poverty or because they were categorically eligible (e.g., received public assistance, were foster children, or were homeless). A child who has been determined to be low income and who is participating in Head Start may continue to be considered low income for another program year. Grantees are provided some flexibility in determining family income and, therefore, eligibility for participation. Specifically, the 1998 reauthorization amendments authorized grantees to consider family income during the 12 months before the month in which an application is submitted or during the calendar year before the calendar year in which an application is submitted. Separate from eligibility requirements, Head Start regulations also require grantees to reserve at least 10% of their slots for children with disabilities. These children must still meet income or categorical eligibility criteria, or else they must be counted toward the capped percent of children from families with income above poverty. The term "funded enrollment" refers to the number of Head Start slots that are funded, not the total number of children served throughout the year (which would be higher, accounting for turnover). In FY2012, there were funded enrollment slots for 956,497 children. Roughly 12% of these slots (113,566) were for children in Early Head Start programs. Table 1 displays funded enrollment levels since FY2001. An unenrolled space (or vacancy) in Head Start programs is defined as a funded space that is vacant for over 30 days. Reasons for underenrollment vary. A grantee's underenrollment may be temporary in nature (e.g., children are being displaced from a particular facility) or more permanent (e.g., changing community demographics, inadequate outreach to new or changing populations of low-income families). Head Start programs are required to maintain waiting lists in an effort to ensure that vacant positions can be filled quickly. However, there are a number of reasons why it can be difficult to fill vacancies quickly. For instance, families on the waiting list may have moved outside of the Head Start service area or may have already enrolled their child in a local preschool program.