As there is a dearth of Spanish-language standardized scales that assess adaptive behavior in children and adolescents with intellectual disabilities (ID), the authors adapted one of the most widely used and studied scales of adaptive behavior in the U.S., the ABS-S:2 (Adaptive Behavior Scale-School, 2nd Edition), and validated it for use in Spain. The authors translated the ABS-S:2 into Castilian Spanish and tested the adaptation with a cohort of 207 school-age children in Burgos, Spain (n = 142 with ID; n = 65 without an ID) to assess the validity and reliability of the translated scale. The translated scale took into account both Spanish language usage and the culture of Spain. As part of their testing of the adapted scale, the authors found that the average scores for the adaptive behavior of children without an ID were higher than those of children with ID. Their findings also showed that the averages obtained in adaptive behavior by children without ID increased with their chronological age; among children with ID, these averages showed a discontinuity in progress. From these data, they concluded that the overall assessment of their adapted ABS-S:2 more than met the quality criteria for use in assessing children and would prove to be a reliable scale to use with Castilian Spanish-speaking children with ID.