Given relevant cultural distinctions across nations, it is important to determine the dimensional structure and normative characteristics of psychological assessment devices in each focal population. This article examines the national standardization and validation of the Adjustment Scales for Children and Adolescents (ASCA) with a nationally representative sample of Trinidad and Tobago schoolchildren (N = 900). ASCA is a 156-item teacher rating scale that measures sociobehavioral adjustment. Results from exploratory and confirmatory analyses yielded the same Overactivity and Underactivity dimensions observed in international samples. The dimensions were scaled using IRT and Bayesian scoring, with scores evincing expected moderate to strong relationships with other teacher observations and weaker relationships with parent observations and reading achievement. Population performance trends are explored and implications are discussed.