Drama, theater and role-playing methods are commonly used in health promotion programs, but evidence of their effectiveness is limited. This paper describes the development, implementation and evaluation of a school-based drama program to enhance social relationships and decrease bullying at school in children in grades 4–5 (mean age of 10.4 years). Students (n = 190) were recruited from two primary schools with similar demographics and socio-economics in the Southern Finland and purposively allocated either to an intervention group or a control group. The drama program included classroom drama sessions, follow-up activities at home and three parents’ evenings concerning issues of social well being during the school year September 2007–May 2008. Data on social relationships in the class room and experiences of bullying were obtained before and after the program using self-completed questionnaire from the same students (n = 134). The response rate was 71%. No differences in socio-demographics existed between intervention group and control group at pretest. The positive effect on social relationships resulting from the intervention approached statistical significance (p = 0.065). Moreover, the positive effect was found to be statistically significant in the high-intensity intervention classes (p = 0.011). Bullying victimization decreased 20.7 percentage units from pretest (58.8%) to posttest (38.1%) in the intervention group (p < 0.05). The study indicates that using applied drama and theater methods in the classroom may improve children's social relationships at school.