Social movements may bring positive social changes. However, escalated levels of violence and delinquency in some campaigns caused public concerns about infringing personal rights and destroying public property. In modern societies, we encourage mutual respect, peace, and appropriate conflict resolutions and avoid the use of aggression across situations. This cross-sectional study examined forgiveness, moral disengagement, and reactive and proactive aggression among different types of young social activists in Hong Kong. Findings would provide insights into intervention strategies for reducing aggressive behaviors in young people and helping them restore their quality of life. Our participants were 1046 local secondary school and tertiary students (583 males and 463 females) aged 12 to 25 years (M = 16.95, SD = 3.29). They completed a questionnaire about their participation in local campaigns, with psychological measures of forgiveness, moral disengagement, and aggression. The respondents were then divided into three categories: non-activists (NA), moderate activists (MA), and activists with delinquent/violent action (ADA). ANOVAs were used to examine the differences between these three types of social activists. Results indicated that ADA reported using more reactive and proactive aggression than NA, and MA reported using more reactive but not proactive aggression than NA. ADA had significantly higher levels of moral disengagement overall than NA and MA. Regarding forgiveness, both ADA and MA had significantly lower levels of absence of negative than NA. Implications for psychotherapy, education, and social policies will be discussed.