Early internalizing and externalizing behaviour problems strongly predict later behaviour problems. We investigated cognitive correlates (executive functioning (EF), Theory of Mind (ToM), and verbal ability (Peabody Picture Vocabulary Task (PPVT) of internalizing and externalizing behaviour (assessed with Child Behaviour Checklist) in 229 3-to-6-year-old children. ToM and EF (r = .446, p < .001), ToM and PPVT (r = .308, p < .001), and EF and PPVT (r = .434, p < .001) were significantly related. Partial correlations, controlling for age, EF, and PPVT, showed that ToM was independently related to internalizing behaviour (r = -.125, p = .030), emotional reactivity (r = -.120, p = .035), anxious/depressed (r = -.141, p = -.016), and withdrawn/depressed (r = -.138, p = .018). Trends were observed for correlations between ToM and externalizing behaviour (r = -.105, p = .057) and aggression (r = -.087, p =.096), while the correlation with attention problems was significant (r = -.119, p = .036). Generalized Linear Models also showed significant differences on externalizing behaviour [Wald Chi-square = 17.8, p < .001] and aggression [Chi-square = 14.9, p = .001], between children with good and poor ToM-performance. In contrast, none of the EF-behaviour correlations remained significant after control for ToM and PPVT, and only the PPVT-withdrawn/depressed correlation remained significant after control for EF and ToM.

It is concluded that cognitive interventions for young children at an increased risk for continued behaviour problems might best be aimed at improving social cognitive abilities.