This study evaluated the implementation and efficacy of the Hands Project – a prevention program for teen dating violence among middle and high school students, implemented during the pandemic. The Hands Project is a brief in-class intervention, targeting the attitudes, personal skills, and the role of bystanders in abusive dating situations with youth. A monitoring process was conducted with 11 classes, and a quasi-experimental evaluation was carried out with 61 students (intervention group n = 45; comparison group n = 16), with pre-test and post-test administration of the Attitudes Toward Dating Violence Scales (ATDV). Program responsiveness and implementation quality were high, and positive significant results were found for female physical violence, indicating a decrease in tolerance for the intervention group, when compared to the comparison group. Discussion reflects on the implications of this study for the implementation and evaluation of teen dating violence programs, and future research regarding this phenomenon.