Childhood behavior problems, encompassing internalizing (e.g., depression, anxiety) and externalizing (e.g., aggression, conduct problems) issues, are prevalent and significantly impact mental health and future well-being. While previous research suggests potential decreases or increases in these problems throughout childhood, influenced by various factors, findings remain inconsistent, often hampered by limitations like small sample sizes or focus on specific populations (e.g., low-income or clinical samples). This study addresses these limitations by utilizing a large, diverse community sample from the Early Childhood Longitudinal Study (ECLS-K:2011) to explore the developmental trajectories of behavior problems and their predictors, acknowledging the likely heterogeneity within the sample. The study hypothesizes that childhood behavior problems are heterogeneous and that individual characteristics (gender, race), family characteristics (socioeconomic status), and psychological characteristics (self-control) influence these trajectories.

Existing research on the developmental trajectories of internalizing and externalizing problems offers inconsistent findings. Some studies suggest stability in internalizing problems and increases or decreases in externalizing problems, while others report decreases in both throughout childhood. Previous work has also explored subgroups based on externalizing problems, but fewer studies have examined subgroups for internalizing problems. The inconsistent findings and limited exploration of subgroups highlight the need for a more nuanced understanding of individual differences in behavior problem development. This study draws on dynamic systems theory, emphasizing the nonlinear and context-dependent nature of individual development, and ecological systems theory, acknowledging the interplay of multiple factors (individual, family, societal) in shaping behavior.

This longitudinal study utilized data from nine waves of the Early Childhood Longitudinal Study of 2010–2011 (ECLS-K: 2011), encompassing teacher-reported internalizing and externalizing problems from kindergarten through fifth grade. After excluding children with special needs and incomplete data, the final sample comprised 11,779 children for internalizing problems and 11,785 for externalizing problems. The Social Rating Scale (SRS) measured behavior problems, self-control, and interpersonal skills. Sociodemographic variables (gender, race, family socioeconomic status) were also collected. Growth mixture modeling (GMM) was employed to identify distinct trajectories of behavior problems and to examine predictors of these trajectories. Model fit indices (BIC, SSABIC, Entropy, aLRT, BLRT) were used to determine the optimal number of classes. All analyses were conducted using Mplus version 7.4 with the full information maximum likelihood (FIML) estimator to handle missing data.

Unconditional GMM revealed three distinct trajectories for internalizing problems: a low-increased pattern (5.88%), a low-stable pattern (87.23%), and a medium-decreased pattern (6.89%). For externalizing problems, five trajectories were identified: a high-decreased pattern (4.05%), a medium-decreased pattern (11.64%), a low-very high increased pattern (0.20%), a low-increased pattern (10.45%), and a low-stable pattern (73.66%). Conditional GMM showed that race, gender, and self-control at Wave 1 predicted internalizing problem classifications. Specifically, non-white race, girls, and children with low self-control were more likely to exhibit the medium-decreased pattern. For externalizing problems, gender, family socioeconomic status, and self-control at Wave 1 were significant predictors. Higher socioeconomic status and self-control were associated with the low-stable pattern. Within-class analyses revealed further nuances in the relationships between predictors and the trajectories of both internalizing and externalizing problems. For instance, race and self-control negatively predicted initial levels of internalizing problems, while gender and self-control positively predicted slopes. Similar complex relationships were observed for externalizing problems across different trajectory groups.

The findings support the hypothesis of heterogeneity in the development of childhood behavior problems. The identification of multiple distinct trajectories for both internalizing and externalizing problems underscores the importance of considering individual differences when designing interventions. The significant predictive roles of race, gender, socioeconomic status, and self-control align with ecological systems theory, highlighting the interplay of individual, family, and broader societal factors. The consistent association of high self-control with more positive trajectories (low-stable patterns) points to self-control as a protective factor. The study's findings have significant implications for prevention and intervention efforts, suggesting the need for tailored approaches based on individual characteristics and developmental trajectories.

This study provides valuable insights into the heterogeneous developmental trajectories of childhood behavior problems and identifies key predictors. The results emphasize the need for individualized approaches to prevention and intervention, targeting specific risk factors and developmental patterns. Future research should investigate the long-term consequences of these trajectories and explore the effectiveness of interventions that address the identified risk factors, particularly for vulnerable groups.

The study relies on teacher-reported data, which might not fully capture the complexities of children's behavior problems. Future research should incorporate parent and child self-reports. The focus on time-invariant predictors might overlook the influence of time-varying factors. Including time-variant predictors in future studies would provide a more comprehensive understanding. Finally, while the study explores trajectories, it does not directly examine the outcomes of behavior problems on later development. Future work should incorporate measures of academic achievement and social-emotional well-being.