This study analyzes how cultural tensions (i.e., ethnic and religious) affect various internal conflicts (e.g., civil war to civil disorder) across different regions. The study also examines the role of governance in mitigating the effects of cultural tensions on the emergence and escalation of conflict. The comprehensive study has 136 countries from 1990 to 2021, and panels are separated by region and OECD status. The study uses two-way fixed effects with Driscoll and Kraay standard errors to account for heteroscedasticity, autocorrelation, and cross-sectional dependence. Although there are some regional variations and nuances, the results indicate cultural tensions are significant determinants of (1) the broad measure of internal conflict, (2) civil wars/coups d’état, and (3) political violence/terrorism. Therefore, one implication is that cultural tension continues to drive internal conflict. A second implication is that even in OECD countries, where institutions and governance structures are robust, cultural tensions can still significantly contribute to the emergence and risks of internal conflict. However, ethnic and religious tensions are less influential in smaller-scale conflicts, such as civil disorders, where government stability is a more important determinant. Furthermore, the study finds that government strength is vital in moderating all forms of internal conflict, indicating that even moderate cultural tensions can escalate into significant conflicts in the presence of weak governance. The study underscores the ongoing importance of addressing ethnic and religious tensions. Policy recommendations to reduce cultural tensions include (1) promoting cultural inclusiveness within societal/political dimensions, (2) promoting tolerance, (3) allowing some autonomy to cultural enclaves, and (4) actively monitoring cultural tensions and policy initiatives.