Recent changes in the reproductive behaviour of women m the rural areas of Bangladesh have occurred at a time when the country has been and still 1s predominantly agricultural and socio-economic conditions poor. Attempts to explain the causes of these changes, especially consideration of the role of family planning programmes, in such an unfavourable context, have generated enormous controversy among academics. This study examines the determinants of these recent reproductive changes in rural Bangladesh over a 13-year period. It uses quasi-experimental design based on comparison between three areas: national rural, Matlab intervention and Matlab control, using time series analysis of the repeated surveys. The changes were measured by two major proximate determinants: demand for additional children and trends in current contraceptive use. The outcome of these two factors, the fertility decline, was also analysed. The specific objective was to examine whether the family planning programme is a determinant of, or a mechanism towards, the changes m reproductive behaviour, and what role other micro and macro factors play in this. The major findings of the study show that the demand for no additional children was generated prior to the fertility decline among rural women of Bangladesh indicating a demand for fertility control. The family planning programme has helped to mitigate the demand for fertility control modifying supply logistics since the late 1970s. In terms of the determinants of reproductive change at the macro, macro and community level, this study documented that reproductive behaviour is strongly affected by biosocial and cultural factors related to macro level social structures existing at the community level. It is less strongly affected by social factors, and weakly affected by economic factors. However, the strong relationship between biosocial and cultural factors and reproductive behaviour changed over the period studied. In all three areas studied, young women who have fewer living children or sons have started using contraceptives though the old women are the major users. Changes m reproductive behaviour have resulted from social change coming in response to land crises, community contextual factors, the Non-Government Organisation programmes, and other macro level social changes occurring in more recent times. These changes affect both the macro and community level social structures related to patriarchy, which, in tum, influence the proximate determinants: the demand for no additional children and the current use of contraceptives. The study suggests that reproductive women in all three areas shared a similar notion of desired family size and level of demand for no more children prior to the fertility decline of the 1980s. This desired family size is much lower than the actual fertility rate and is probably affected by the prior mortality changes and improved survivorship. During the period studied, desired family size reduced further but it reduced equally, despite a different level of family planning intervention in one of the three areas. With this same level of desired family size, Matlab family planning intervention with an efficient supply logistics show an extremely successful mechanism for increasing contraceptive use and there reducing fertility levels in the mid 1970s, while high fertility in the other two areas began to decline in the 1980s. Finally, examining the four possible postulates, the present study found that no one postulate alone could explain the changes in reproductive behaviour among rural Bangladeshi women. Further in-depth study is needed for better understanding of the dynamics of these reproductive changes.