The purpose of this study was to examine the relationship among measures of cognitive functioning, adaptive behavior, and language acquisition for a referred preschool population. The subjects were 115 preschoolers (75 boys and 40 girls) under the age of 6 years who had received a psychoeducational battery of tests for either suspected learning difficulties, emotional problems, or attention disorders. This data was collected from the archival records in a children's hospital.Pearson product moment correlations were used to examine the relationship among measures of cognitive functioning, adaptive behavior, and language acquisition. Correlation matrices were formulated to investigate the relationship.Three groups were delineated dependent on the instrument used to assess the preschoolers: Group 1 received the Bayley Intelligence Scale for Children and the Wisconsin Adaptive Behavior Scale; Group 2 received the Bayley Intelligence Scale for Children and the Vineland Adaptive Behavior Scale; and Group 3 received the Stanford-Binet LM, the Vineland, and the Preschool Language Scale.The correlations obtained in Group 1 were all statistically significant (p<.01); these correlations for cognitive functioning and adaptive behavior were the highest of all the three groups. In fact, considerably higher than might be predicted after the review of the literature that contends that cognitive functioning and adaptive behavior are separate yet related constructs. Moderate correlations between cognitive functioning and adaptive behavior were found for the other two groups in alignment with earlier studies.In examining cognitive functioning and adaptive behavior for this referred preschool population it seems that the relationship changes as the child gets older. This study was not longitudinal; however, a greater separation of the constructs of cognitive functioning and adaptive behavior existed for the older child in this sample.In addition to examining the relationship between cognitive functioning and adaptive behavior, this study also looked at language acquisition in relationship to cognitive functioning and adaptive behavior. Statistically significantly high correlations were found for cognitive functioning and language acquisition for this study. The Preschool Language Scale Expressive subdomain was slightly more highly correlated with the Stanford-Binet LM than the Preschool Language Scale Receptive subdomain. This is consistent with the Vineland's Expressive subdomain correlating higher with the Stanford-Binet LM than the Vineland's Receptive subdomain. This suggests the age of the child has something to do with measuring language acquisition in the areas of receptive and expressive language.Given the moderate to high correlations for cognitive functioning, adaptive behavior, and language acquisition for this referred preschool population, it was concluded that measures of adaptive behavior and language acquisition assess constructs similar, yet distinct to cognitive functioning. Therefore, they are both valuable components in comprehensive assessment especially of children "at-risk". / Department of Educational Psychology