Objective: To examine associations of teacher-rated conduct problems (CP) and hurtful and uncaring behaviours (HUB) at age 6 and 10 with criminal convictions up to age 24 among 1593 males and 1423 females, and to determine whether aggressive behaviour at age 12 mediated the associations of CP and HUB with criminal convictions. Method: Teachers assessed HUB and CP at ages 6 and 10 and ratings above the 90th percentile at each age and within each sex were used to assign participants to 1 of 4 groups. Teachers assessed proactive, reactive, indirect, and verbal aggression at age 12. Juvenile and adult criminal records were obtained. Results: High CP and HUB males, aged 6, were 4 times more likely than males with lower ratings to acquire convictions for violent crimes and 5 times more likely to acquire convictions for nonviolent crimes by age 24. High HUB and CP females, aged 6, were 5 times more likely than females with lower ratings to have a conviction for a nonviolent offence by age 24. Among males, both aged 6 and 10, high HUB without CP were associated with elevations at risk of convictions for violent and nonviolent crimes, while among females the elevations at risk were limited to convictions for nonviolent crimes. Different types of aggressive behaviour mediated associations of high HUB and CP with subsequent criminal convictions, but not the association of HUB without CP and crime. Conclusions: Teachers in elementary schools rated behaviours that, from age 6 onward, significantly predicted criminal convictions into early adulthood.