Youth violence is a significant public health issue in Thailand where most people who are injured are vocational college students. There is a need to identify methods whereby such violence can be prevented. We trialed a group program in a technical college in Thailand with 23 students who received a modified version of aggression replacement training. We then compared their results with those of 24 students who did not receive any intervention or preintervention at 1 and 3 month followups. Although we found little evidence supporting the effectiveness of the intervention, participants in the intervention group suggested in the followup in-depth interviews that they felt more able to avoid or ignore provocation, and that they thought more about the consequences of aggressive behavior than they did prior to the intervention.