The need for prevalence data and distinctive ways of identifying and confirming the presence of language impairments in African American children is acute. In the absence of appropriate information of this type, African American children who are speakers of African American English (AAE) are high risk for misidentification as language disordered and may be receiving costly services that are not needed. Conversely, children which disorders may go undetected and fail to reach their academic and vocational potentials in the absence of needed interventions for language problems. The purpose of this project is to establish prevalence estimates for Specific Language Impairment (SLI) in African children, and to investigate the potential of tense as a clinical marker for ALI in AAE- speaking children. Subjects will be approximately 750 4 and 5 year old African American children identified at the time of school entry. Children with SLI will be identified from this sample as well as one group each of age and language-matched controls. All children will participate in a language screening protocol and those who fall the screening will be administered a follow-up diagnostic protocol. Along with performances from a randomly selected set of children who passed the screening, the diagnostic information combined with specific probes of verb morphology will be examined for potential clinical markers. Compared to recently reported prevalence estimates for majority children, it is anticipated that estimates for this African American sample will vary relative to socioeconomic status. Outcomes will provide prevalence importance for many public policy decisions and contribute to current theorizing regarding the cross-linguistic generalizability of clinical markers, and the nature of SLI.