There were 65 third-year medical students and 59 pediatric residents who participated. The intervention was a 40-minute multimedia program that teaches how to counsel parents about childhood aggression. Comparing pre- and 2-month postintervention data, there was an increase in the proportion of medical students (11% pre vs 92% post; P < .001) and residents (3% pre vs 95% post; P < .001) who felt that their ability to counsel parents about hurtful behavior was high or very high. Compared with baseline, a higher proportion of trainees at the 2-month follow-up recommended redirecting (11% pre vs 69% post; P < .001), promoting empathy (13% pre vs 42% post; P < .001), and not using physical punishment (25% pre vs 50% post; P < .001). A brief, independently viewed curriculum addition expanded the repertoire of health care trainees related to counseling parents about childhood aggression. These findings have implications for violence prevention.