In clinically referred children, boys and those with disorganized mother–child attachments tend to show the most maladaptive externalizing trajectories; however, additional research is necessary to test whether these findings hold in a community sample. Therefore, 235 community children (106 boys) were followed from ages 6 to 15 years across six time points. Multiple-group linear growth curves with mother–child attachment as a time-invariant covariate were fit to the data to explore externalizing trajectories for boys and girls. Results showed that boys had higher initial externalizing levels than girls, and children generally experienced a decline in symptoms over time. No significant trajectory differences were found for girls, and boys with different attachment classifications did not differ on their initial externalizing levels; however, boys with avoidant attachments (with resistant attachments trending) experienced a steeper decline in externalizing symptoms longitudinally. Implications for intervention and prevention are discussed.