After three decades of research on the demographic significance of family planning programmes, a consensus has emerged that family planning programmes can constitute a fertility determinant. The central question now is not whether family planning programmes can have an impact, but what ingredients are required for formal programmes to interact effectively with the elements of demand in different settings. This is particularly true in such areas as South Asia and sub-Saharan Africa where social and economic conditions are unfavourable to fertility regulation and where family planning programmes are constrained by limited demand for birth control and weak capacities to organize large-scale service delivery systems. This volume presents an overview of the research evidence on the demographic role of family planning programmes. The subject is addressed from perspectives that are prominent in the economic and sociological literature on the nature of demand for contraception, and how that demand relates to such programme functions as normative change, legitimation of birth control, and supply of services. Authors challenge the assumption implicit in much of the literature, that demand- and supply-side determinants are conceptually distinct: the two can interact, each stimulating growth in the other. Methodological and theoretical issues in the measurement of programme effect on fertility are reviewed, and the practical utility of theory in the design of sociologically appropriate family planning programmes is appraised.