LAUSR

This study aimed to identify gender-specific co-developmental trajectories of internalizing and externalizing problems from middle childhood to early adolescence, along with key environmental and individual predictors among Chinese youth. A total of 1653 Chinese elementary school students (Mage = 9.40; SD = 0.51; 54.57% boys) participated in assessments at six time points, using 6-month assessment intervals. Parallel process latent class growth modeling identified four trajectories for boys: Congruent-low (65.74%), moderate-decreasing internalizing and moderate-stable externalizing problems (18.40%), high increasing-internalizing and low-stable externalizing problems (8.20%), and high decreasing-internalizing and low-stable externalizing problems (7.65%). Three trajectories were identified for girls: Congruent-low (81.09%), moderate co-occurring (7.19%), and high increasing-internalizing and low-stable externalizing problems (11.72%). Multivariate logistic regression analyses revealed that peer victimization served as an environmental risk predictor for the adverse co-developmental trajectories of internalizing and externalizing problems for boys and girls. High sensation-seeking and low self-control served as individual risk variables predicting the trajectories of high increasing-internalizing and low-stable externalizing problems, and low self-control also predicted the trajectories of high decreasing-internalizing and low-stable externalizing problems for boys. The findings highlight the importance of gender differences in understanding the progression of internalizing and externalizing problems and inform effective strategies for prevention and intervention.