This article presents the design, nationwide standardization, and validation of the Adjustment Scales for Children and Adolescents (ASCA), a device that bases psychopathology on pervasiveness of problem behavior across multiple situations. A norm sample of 1,400 5- through 17-year-old Ss was stratified according to the U.S. Census by age, gender, academic level, ethnicity, handicapping condition, national region, community size, and parent education. An additional 1,418 Ss composed supplementary validity generalization samples, and all Ss were evaluated by teachers using ASCA. Exploratory and confirmatory components analyses revealed 8 distinct and reliable syndromes, 6 of which are core syndromes found to be generalizable across age, gender, and ethnicity: Attention-Deficit Hyperactive, Solitary Aggressive (Provocative), Solitary Aggressive (Impulsive), Oppositional Defiant, Diffident, and Avoidant. Concurrent and discriminant validity were demonstrated for the core syndromes, and their use in practice and future research is discussed.