Group-based modeling techniques are increasingly used in developmental studies to explore the patterns and co-occurrence of internalizing and externalizing problems. Social competence has been found to reciprocally influence internalizing and externalizing problems, but studies on its associations with different patterns of these problems are scarce. Using data from a Finnish longitudinal normal population sample, trajectories of internalizing and externalizing problems were formed using the Child Behavior Checklist completed by the mother at the child's age of 4- to 5-years-old, 8- to 9-years-old, and 16- to 17-years-old (N?=?261). The results indicate that adolescent's self-reported internalizing and externalizing problems based on the Youth Self Report were associated with the trajectories of internalizing and externalizing problems. Social competence both in early childhood and in adolescence was poorer among children with chronic internalizing problems and among those with adolescent-onset externalizing problems. One-third of the children who had a chronically high level of internalizing problems had an initially high but decreasing level of externalizing problems, while 33% of the adolescents with adolescent-onset externalizing problems had a chronically high level of internalizing problems. School psychologists are encouraged to screen for internalizing problems from children with behavioral, academic or social problems.