Background: Asthma is a chronic health condition that has a disproportionate effect on low-income minority children who reside in large urban areas. African American children report significantly higher rates than the general population of children and have more-severe asthma and poorer outcomes. This article describes the prevalence of asthma in a particularly vulnerable group: children aged 2-5 participating in Detroit Head Start programs. Methods: Health screens were distributed to caretakers of all children attending 6 Head Start agencies. Caretakers of children identified with active asthma symptoms were asked to complete an in-depth phone interview regarding their child's asthma. Results: Data collected from 3,254 children (78% African American) revealed that 27% met criteria for probable asthma. Of those with persistent symptoms, 26% were undiagnosed, and 21% were untreated. Baseline data (n = 675) showed that 95% had a regular doctor, but 36% had had no health care visit for asthma in the previous year. Of children with a history of asthma episodes, more than half reported 3 or more episodes in the preceding year. Forty-three percent of caretakers had discussed their child's asthma with Head Start, and 31% had an asthma action plan on file with Head Start. Conclusions: Asthma remains a significant problem in this population, especially for African Americans, as evidenced by high levels of undiagnosed children with persistent symptoms and questions regarding the care they receive. Head Start is a way to reach young children with asthma, but may need help to develop the capacity to assist families. (Contains 5 tables.)