This report presents an overview of the Vineland Adaptive Behavior Scales and two measures of cognitive ability: the Kaufman Assessment Battery for Children (i.e., sequential and simultaneous processing, levels of achievement) and the revised Peabody Picture Vocabulary Test (i.e., listening vocabulary). These three instruments are applied and directly compared to demonstrate the interplay between adaptive behavior and cognitive functioning in the broader context of a pediatric setting. Two hypothetical case histories are discussed, one in which the child's levels of adaptive functioning are adequate while cognitive functioning is low; and a second one in which the reverse phenomenon is true, namely, high levels of cognitive functioning are coupled with impairments in adaptive functioning. The direct comparisons between the various areas of functioning are made possible by large Vine/and standardization samples of children whose abilities were assessed by all three instruments.