The core syndrome factor structure of the Adjustment Scales for Children and Adolescents (ASCA) was examined with a sample of 375 randomly selected Canadian youths in a large western city. The 6 ASCA core syndrome raw scores produced an identical two-factor solution as observed in samples of American youths. Principal axis exploratory factor analysis with varimax and promax rotations produced similar factor structure coefficients. It was concluded that the ASCA measures two independent dimensions of youth psychopathology (overactivity and underactivity), similar to the conduct problems/externalizing and withdrawal/internalizing dimensions commonly found in the child psychopathology assessment literature. (Contains 5 tables and 2 notes.)