In sub-Saharan Africa, large-scale measurements (for an entire country or region) show that the use of modern contraceptive methods is increasing, but slowly, giving the impression that change in this field will inevitably take time. To gain a better understanding of the reasons why the spread is so slow, particularly in rural areas, we made a detailed study of the history of contraception in a rural community in Bandafassi, Senegal. Using several information sources we were able to track the increase in contraceptive use year by year and examine the factors at work. The study presented here shows that, contrary to received wisdom, contraceptive use can spread rapidly in a rural area of Africa with few socioeconomic advantages, but that its diffusion is difficult to measure due to considerable under-reporting, and is by no means guaranteed over the long term.