Since the 1950s, the fertility rate has fallen in Peninsular Malaysia, owing in part to the rising percentage of couples who practice contraception and to the increasing effectiveness of the methods they use. This report examines individual women's histories of contraceptive method use, using data from the Malaysian Family Life Survey, looking especially at the types of contraceptive changes they make over their reproductive careers. The vast majority of new acceptors of modern methods had not used any method of contraception previously. Hence, the trend toward increasingly effective contraception was not mainly due to individual women substituting modern for traditional contraception, but rather to younger cohorts of women accepting modern, effective methods, primarily the pill. If the results for Peninsular Malaysia in the period between World War II and 1975 characterize other countries, they have important policy and program implications, including: family planning programs appear to induce nonusers to begin practicing contraception, and some users of less effective methods to switch to more effective ones; the family planning program in Malaysia may have increased the incidence of temporary contraception use; increases in education should improve patterns of contraceptive practice; and expansion of the number of methods available to couples should increase contraceptive prevalence.