In a four-year longitudinal study, changes in and continuity of behavioral and emotional problems were examined in 814 subjects from kindergarten to primary school. Mental health problems were assessed by means of the Child Behavior Checklist (CBCL). The distribution of the CBCL broadband groups revealed a high level of continuity of internalizing symptoms over the four-year period and a shift from externalizing symptoms at baseline towards a combination of internalizing and externalizing symptoms at follow-up. The presence of mental health problems at follow-up was correlated with gender (higher amongst boys), pre-existing mental health problems at baseline, and separation or divorce of the parents, but not with single-family status or the age and educational level of the mother. The increasing number of children with a combination of internalizing and externalizing symptoms demonstrates the increasing complexity of child mental health problems in the developmental span from preschool age to school age.