The purpose of this pilot study was to evaluate the effect of a dating violence prevention program on attitudes justifying aggression and on physical and psychological aggressive behaviors. The study was conducted using a convenience sample of 104 high school students (52.9% females), with an average age of 15.44 years (SD= 1.12). Participants were assessed through self-report scales administered one week before and one week after program implementation. The results show a significant decrease in attitudes that justify the use of physical and psychological aggression in dating relationships (both when they are perpetrated by a male, p< .01, and when they are perpetrated by a female, p< .001), with no differences as a function of respondents’ sex or prior involvement in dating aggression. There were no changes in the levels of actual aggressive behaviors. It is concluded that the prevention program shows promise for preventing dating violence among adolescents. Nevertheless, future research is needed to clarify the long-term effect of the program, especially on aggressive behaviors.