Objective: This study was designed to examine whether a school-wide antibullying program, effective in reducing incidents of bullying, can also reduce the harm associated with victimization. Specifically, we test whether baseline victimization moderates the KiVa program intervention effects on school perceptions, depression, and self-esteem. Method: Relying on a randomized control sample consisting of 7,010 fourth to sixth grade Finnish elementary school students, self-report data were examined using multilevel modeling across 39 intervention and 38 control schools over a 12-month period. Results: The KiVa program was particularly effective in facilitating perceptions of a caring school climate among students who were most victimized before the intervention, while program benefits on attitudes toward school did not vary by level of victimization. The intervention effects on depression and self-esteem were strongest only among the most victimized sixth graders. Conclusions: The results suggest that antibullying programs designed to improve the school ecology can alleviate the plight of the victimized and underscore that harm reduction should be assessed by testing risk x intervention effects when evaluating effectiveness of such programs.