The trajectories of internalizing and interpersonal behaviors from kindergarten through fifth grade were studied using univariate and bivariate latent curve models. Internalizing behaviors demonstrated a small, yet statistically significant, linear increase over time, while interpersonal behaviors showed a small, yet statistically significant, linear decrease. There were individual differences in trajectories, and predictor variables accounted for some of this variation. In kindergarten, girls had more interpersonal behaviors than did boys. Children from higher SES families or with higher initial levels of externalizing behaviors had more internalizing behaviors and fewer interpersonal skills. One key finding from this study was that interpersonal and internalizing trajectories demonstrated a strong association. Increasing internalizing slopes were associated with decreasing interpersonal slopes. Establishing this empirical relation is necessary for understanding the developmental trajectory of these related behaviors, as well as important individual differences over time. (Contains 1 footnote, 3 tables, and 2 figures.)