In Canada, the baby boom unfolded differently in the various provinces, particularly in the two most populous provinces of Quebec and Ontario. In the latter, the picture is the usual one, with an increase in both fertility and nuptiality which, together, are responsible for a significant increase in total fertility rates. In Quebec, where the first demographic transition was not yet complete at the onset of the baby boom, the nuptiality increase was also very strong, but married women actually gave birth to fewer children, not more, during the baby boom. In this paper, we use two pieces of retrospective information from the 1981 census—the age of women when they were first married and the number of children born to them—to investigate the differences in cohort fertility rates for married women born between 1900 and 1940, and the corresponding parity ratios. We also use multinomial logistic regression models to assess the impact of religion, ethnic origin, education, and province of residence on the fertility outcomes of these women, while taking into account their age at marriage and the duration of the marriage. Results show 1) diverging patterns for Catholic and Protestant women, yet the fertility levels in these two groups were remarkably similar for the last cohorts of women; 2) the positive impact that marrying at a younger age and having a longer marriage had on fertility, although this was not sufficient to account for the rise in Protestant fertility; and 3) the persistence of an educational gradient in fertility outcomes, even though the gap narrowed between categories. These results are generally in line with what more fine-grained analyses of the baby boom in some European countries have shown recently.