This article analyses the development of rural fertility in Belgium between 1880 and 1939, questioning, on the one hand, the heterogeneity of behaviour and, on the other, the impact of major cyclical events — the First World War, the 1929 economic crisis and the emergence of totalitarian regimes — which characterised this period. The analyses combine a classical cross-sectional approach and a longitudinal approach based on the exploitation of back data from the 1961 and 1981 population censuses. Contrary to the ideas received, the fertility behaviour of the rural population is not homogeneous. Some of them position themselves as pioneers of fertility transition. For others, the start is later, but once started, the decline in fertility is rapid. Finally, some are characterised by a later, slow and hesitant transition. While the effect of World War I has little on fertility curves, the impact of the economic crisis of the 1930s on demographic indicators is more noticeable. The age at marriage and the timing of fertility are decreasing, while the fertility rates of the generations affected by the crisis are decreasing. The importance of these effects varies across rural environments.