The aim of the study was to evaluate the efficacy of an intervention using indirect intergroup contact for improving intergroup attitudes in schools, in particular anti-Roma prejudice. Vicarious contact—a form of indirect intergroup contact—can be experienced through fictional book characters, who can serve as positive role models in terms of intergroup attitude improvement. A vicarious contact experiment was conducted with sixth grade students (N = 177) from three Slovak elementary schools, using passages from the Harry Potter series. A three-group pretest-posttest design was adopted; experimental condition 1 involved reading passages without subsequent discussion, experimental condition 2 involved reading the same passages followed by a discussion, while the control group was not involved in any activities. There was a significant improvement of intergroup attitudes in experimental condition 2 compared to the control group, while condition 1 did not show any such improvement. The first contribution of the study is in tackling conceptually distinct mediators of the intervention’s effect – perspective taking and narrative transportation. The second contribution is in demonstrating the added value of discussion in interventions focused on prejudice reduction in schools.