A decade has elapsed since a project was launched in Matlab, Bangladesh to test the hypothesis that contraceptive services can induce and sustain fertility decline in a rural traditional population. The demographic impact of this project has been pronounced, lending support to the view that supply-side policies can succeed even where institutional supports for demand are weak. This paper reviews the relationship between the Bangladesh climate of demand and the Matlab system of supply with the aim of explaining how such effects arise. A sociologically appropriate system of supply can induce fertility change in a society where such change would not spontaneously arise. The study of programs and the "sociology of the supply side" thus deserve the same degree of rigor accorded to research on the "sociology of demand."