The early identification and remediation of emotional or behavior disorders are high priorities for early-childhood researchers and are based on the assumption that problems such as school failure can be averted with early screening, prevention, and intervention. Presently, prevalence, severity, and topography of mental health needs among low-income preschoolers and their families have not been well documented. Tools for screening and intervention for behavior problems in preschool children are few and many of those tools have not been studied within diverse Head Start systems. In this study, five instruments of symptoms and functional impairment, completed by teachers and two completed by parents, were obtained on a sample of 1,781 Head Start children from diverse racial and ethnic backgrounds from the Head Start Mental Health Research Consortium. Clinical cut-off scores were used to identify children who could be considered at relatively serious risk for emotional or behavioral disorders. At-risk classifications using clinical cut-offs at both 1.0 and 1.5 standard deviations for each measure were examined singly and in combination and then compared to the overall sample for age, gender, and ethnicity. Identification of children considered at risk ranged from a low of 1% to a high of 38%, with evidence of differential effects on age, gender, or ethnicity for some individual measures, but these tended to diminish when combinations of symptom and impairment measures were used. Implications for choosing instruments to establish eligibility for emotional or behavioral disorders in preschoolers are discussed. (Contains 10 tables.)