A population scientist analyzed data on 1092 15-50 year old, ever-married women (1976-1977 Family Life Survey) living in Malaysia to determine how much they knew about breast feeding as a contraceptive method and whether this perception moderated their use of other contraceptives. Most women (61.6%) believed it was difficult to conceive while breast feeding, but a sizable percentage (38.4%) did not hold this belief. The most important determinants of the perception of the contraceptive effect of breast feeding were being Chinese and the desire to stop having children (odds ration [OR] = 1.75 [p .01] and 1.37, respectively, [p .05]). Women who wanted to stop childbearing were 61% more likely to use an effective contraceptive (oral contraceptive [OC]) than those who did not want to stop childbearing (p .01). Knowledge about the contraceptive effect of breast feeding did not affect either the duration of breast feeding or contraceptive use. Yet, education did play a significant role in OC use (OR for at least secondary education = 2.33). Moreover, younger women were more apt to use OCs than older women (OR = .93; p .01). Thus, modernization as evidence by the relationship between education and age with OC use was most likely the reason for the decline in breast feeding and the increase in contraceptive use. Evidence after the survey indicated that the decline in breast feeding had slowed and had even increased. Therefore, modernization appeared to be influencing both an increase in breast feeding and in contraceptive use.