The present study assesses how education impacts religiosity. Education is instrumented using the changes in the Canadian school leaving age laws. The data are from the Canadian General Social Surveys collected between 1990 and 2011. The effects of education on both affiliation status and religious attendance are considered. Education is found to cause a higher likelihood of unaffiliation and a considerably lower frequency of religious attendance. The fall in the religious attendance rates is found to be stronger among Roman Catholics. Possible channels of impacts are explored.