This study assesses the predictive validity of the Phelps Kindergarten Readiness Scale (PKRS) for later academic achievement and explores the utility of a domain-specific measure of kindergarten readiness. Kindergarten readiness scores were significantly correlated with both math and language arts achievement as measured by New York State fourth-grade assessments for 148 students in a suburban, northeastern public school. In addition, each of the PKRS domains (Verbal, Perceptual, and Auditory) was correlated with later academic achievement. Two simultaneously calculated regression analyses showed that language arts skills were best predicted by the Verbal and Auditory domains of the PKRS and that math achievement was more complexly determined by all three readiness domains. Structural equation modeling using AMOS-4 showed that the latent construct readiness, as measured by the PKRS domain scores, was positively and significantly related to the latent construct academic achievement. Finally, this relationship held when age, gender, and behavioral indices at the time of kindergarten screening were used as moderator variables. (Contains 2 tables and 1 figure.)