In this study, we explore the relationship between Koranic and formal education. The study employs OLS and IV empirical strategies. Both strategies show that child Koranic education has negative and significant impact on formal schooling, with IV estimates considerably higher than OLS estimates. OLS estimates are robust to another of large number of relevant variables. IV results are robust to the same set of covariates as used under OLS. Furthermore, the instruments used are equally strong, and formal and indicative tests suggest that these instruments are plausibly valid. The findings make a very strong case for policy directed at integrating Koranic education into formal education.