This study empirically tested the effects of ‘Gratitude Development Program’(based on teaching of ‘awareness of grace and requital of grace,’ the core doctrine(thought of Grace) of Wonbuddhism) on adolescents’ gratitude disposition and spirituality. We examined the implication of gratitude in the teaching of ‘awareness of grace and requital of grace’ in Wonbuddhism thoughts and developed a gratitude development program based on the theory. In order to test the effects of our developed program on adolescents, we adopted pre & post controlled experimental design for senior high-school girls. 46 of subjects were respectively assigned to both groups of experiment (23 girls) and control(23 girls). The program was applied only to the experimental group for 12 weeks. Scales of gratitude disposition and spirituality were measured pre and post experiment period. Analysis was conducted by ANOVA of repeated measure and ANCOVA including the pre-measures. Results showed significant increases of gratitude disposition and spirituality in experimental group compared to control group after program. We discussed the implications of these results on adolescent developments.