A primary concern with kindergarten readiness assessment is the lack of validity of the devices that are employed by various school districts (Meisals, 1989). The purpose of this study was to determine the concurrent validity of the Kindergarten Diagnostic Instrument (KDI; Robinson & Miller, 1986), using the Developmental Indicators for the Assessment of Learning-Revised (DIAL-R; Mardell-Czudnowski & Goldenberg, 1990) as the criterion. Both instruments were administered to a group of 82 children the summer before, or during the first two weeks of, the kindergarten year. Results of a Pearson product-moment correlation (r=.68) indicated that there was a significant correlation between the two instruments. A Pearson Product-Moment Correlation Matrix, illustrating the relationships between KDI subtests and DIAL-R Total and domain scores, shows that the Concepts domain is significantly correlated with the most KDI subtests. Stepwise multiple regressions indicate that 59% of the DIAL-R Total score is accounted for by KDI subtests. The KDI seems more appropriate in that in addition to determining readiness, the KDI identifies deficit areas and prescribes specific remediation suggestions. (author abstract)