This study examines the intermediate determinants of fertility in Sri Lanka by making use of the data collected in the 1982 Sri Lanka Contraceptive Prevalence Survey and the 1987 Sri Lanka Demographic and Health Survey. The analysis shows that the most important inhibitor of potential fertility is deliberate control. The marital structure of the population is also an important fertility-inhibitor, but lactational infecundability is increasingly becoming an unimportant contributor. The findings show the success of the family planning program in Sri Lanka, which propelled fertility to a substantial lower level. Achievement of the replacement level fertility by the turn of the century, set by the Sri Lankan government, would largely depend on the efforts to increase the quality and quantity of contraceptive use and the duration of breastfeeding.