Co-occurring internalizing and externalizing behavioral problems: the mediating effect of negative self-concept.

While a large body of research consistently finds that internalizing and externalizing problems are closely related and commonly co-occur, the literature is mixed regarding the unique and shared risk processes in the development of both domains of problems. The present study examined the nature and timing of relationships between internalizing and externalizing problems as well as the mediating effects of negative self-concept on both. Using a developmental cascade model as a guiding framework, we conducted a cross-lagged panel modeling on a sample of 2,844 Korean fourth graders (54% boys and 46% girls) followed over 4 years. Findings suggest that internalizing and externalizing problems were reciprocally reinforcing, each leading to increases in the other indirectly through the mediating influence of negative self-concept. Negative self-concept exacerbates the development of both internalizing and externalizing problems, which in turn further undermines one's self-concept. Although there were significant gender differences in the stability of internalizing and externalizing problems, the developmental pathways between negative self-concept and both internalizing and externalizing problems held for both boys and girls. Implications for future research and intervention are discussed.