Head Start programs are required to set aside at least 10% of program slots for children with disabilities, but the percentage of children with disabilities served varies depending on the criteria used and source of the information. This study used the Head Start Family and Child Experiences Survey (FACES) 2000 data for a nationally representative sample to identify subgroups of children meeting three different criteria for having a disability or developmental delay. Results indicated that about one-third of children in Head Start (33%) met one or more of the criteria for a disability or delay, about one-third of those children (33%) met criteria for two or for all three of the subgroups. However, only 8% of children in Head Start had an Individualized Education Program (IEP). Children with disabilities or delays, regardless of the subgroup criteria used, had higher levels of many other risk factors associated with poor developmental and school readiness outcomes. They also exhibited poorer performance on early literacy, social, and behavioral measures both at entry into Head Start and at the end of kindergarten compared with children not in each of those subgroups. Implications of the findings for screening and assessment, serving children in Head Start programs, and the need for linkages between Head Start programs and the preschool special education system are discussed. (Contains 7 tables and 2 figures.)