The aim of this study was to comparatively investigate the predictability of religiosity/spirituality and affective moral reasoning levels of Muslim and non-Muslim students in Muslim societies on their generative altruism. The data of the study were based on a sample of 6722 students in 9th, 10th, 11th, and 12th grade in 10 countries for which data collection and data entry were performed in Wave 1 of Advancing Education in Muslim Societies 2018-2019 fieldwork. Religiosity/Spirituality Scale, Affective Moral Reasoning Scale, and Generative Altruism Scale for Muslim and non-Muslim students were utilized for data collection. T-test and effect size were used for comparing sample means while the Multiple Linear Regression Analysis method was utilized in the regression analysis. The research results showed the level of generative altruism of Muslim students was statistically significantly higher than their non-Muslim peers. It was concluded with the regression model that religiosity/spirituality and affective moral reasoning levels explained generative altruism of Muslim students by 21% and non-Muslim students by 30%. What was noteworthy in this study was that the affective moral reasoning is a stronger predictor of the generative altruism of both Muslim and non-Muslim students than religiosity/spirituality. In light of these results, recommendations were provided about activities that can be conducted on students' generative altruism and future research.