This report discusses the construct and criterion-related validity of the Nebraska Wisconsin Cognitive Assessment Battery (NEWCAB), on the basis of pooled regional data collected in Iowa, Kansas, Nebraska, and Wisconsin on a 3-year longitudinal sample of 107 6-year-old, 141 7-year-old, and 160 8-year-old children. Designed to assess the cognitive development of children 3 to 5, 6 to 8, and 9 to 11 years of age, the NEWCAB assesses qualitative changes in intellectual functioning across preoperational and concrete operational Piagetian stages. Operations were assessed through 16 tasks differentially assigned according to difficulty and age levels. The three sections of the NEWCAB reflect three selected aspects of cognitive functioning: Relations, Classifications, and Number and Length. Contents of this report focus first on the objective, design, and sampling procedures of the longitudinal study, the Life Span Analysis of Mental and Social Development of Rural Children, for which NEWCAB was especially developed. Subsequently, the development, validity, and reliability of the NEWCAB, based on Nebraska data, are reported. Then, the validity of NEWCAB, with regard to regional data, is discussed. It is tentatively concluded that the construct and criterion-related validity of the NEWCAB are empirically verifiable and that the battery has potential for use in assessing children's cognitive development. (RH)