A child's acquisition of adaptive behavior and skills may constitute his or her most important goal during infancy and early childhood. In addition, adaptive behavior data often are required when making decisions under Part C of the 2004 Individuals With Disabilities Education Improvement Act. This study reports the results of a factor analysis of date on 1,350 young children, ages 0-5 years, who constitute the standardization sample of the Adaptive Behavior Assessment System-II (Harrison & Oakland, 2003). The results indicate that the constructs measured by the Adaptive Behavior Assessment System-II for boys and girls are similar, that the skill areas function similarly on corresponding domains for the boys and girls, and that the intercepts are equal for boys and girls for the functions relating skill areas to the factors. Support was found for a one-factor model. The authors discuss the possible uses of Adaptive Behavior Assessment System-II data in reference to diagnostic, classification, intervention, and progress monitoring. (Contains 3 tables and 1 note.)