A three-wave longitudinal study design with two 6-month intervals was used to examine thestability and change in Internalizing, Externalizing, and Total Problem behavior among childrenand adolescents referred to outpatient mental health services. Our results indicated highstabilities for parent ratings of child psychopathology across a 1-year interval. Additionally, wefound decreases in the level of problem behavior. Interindividual differences in change werefound for Total Problems and Externalizing behavior but not for Internalizing. While both thechild's temperament and intelligence level and family relations were related to theinitial level of parent-rated problem behavior, only intermediary stressful life events had aninfluence on the rate of change of child psychopathology.