Mongolian fertility decline has received only limited analysis in the demographic literature. Using the 2003 Reproductive Health Survey of Mongolia the classical proximate determinants of fertility framework proposed by Bongaarts is applied here in order to analyse which factors shape period fertility. The results indicate that the fertility-inhibiting effect of contraception contributed to reduce period fertility by 54.2% from its theoretical maximum, while induced abortion accounted for only 6.1% of the reduction in fertility. Compared with previous studies made in the early 1990s, these results show that important changes in the control of reproduction took place in Mongolia during the fertility transition. In order to assess the changes implied by the transition to democracy and market economy, the proximate determinants of fertility are estimated for the year 1994. The results show that the importance of induced abortion in the determination of fertility level has reduced and that the use of modern contraception has increased progressively and contributed most in determining fertility level in 2003.