Despite an expanding economy in the postWorld War II period, declining infant mortality and an expressed desire of the population to limit childbearing, levels of fertility in Puerto Rico remained high until the early 1950s. Soon afterward, however, fertility began to decline sharply. Between 1950 and 1977, the total fertility rate fell by 48 percent-from 5.2 to 2.7 children per woman. In the early stages of the decline, most of the reduction in fertility levels was concentrated among women 25-39 years of age; by 1960, the decline had accelerated and spread to include both older and younger women of reproductive age. Much of the decline in fertility between 1950 and 1960 was due to the increasing prevalence of female sterilization-and, in the latter half of the decade, to its earlier timing. By 1965, one-third of ever-married women aged 20-49 had been sterilized, twofifths of them before the age of 25. Such levels are higher than those for other countries for which data are available. Levels of female sterilization in Puerto Rico appear to have peaked in the late 1960s, declining slightly in the early 1970s. In 1968, 35 percent of ever-married women aged 2049 had been sterilized. In 1974, the level among such women was 30 percent. Despite this decline, levels of sterilization in 1974 were almost as high as those in 1965. Between 1965 and 1974, sterilization rates were high among women who had been in their 20s in 1965, and moderate among women who had been in their late 30s. Over the same period, there were substantial declines in the prevalence of sterilization among women with one or two children, and some increases among women with five to seven children ever born. Levels of male sterilization remain low. Several factors other than female sterilization appear to have contributed somewhat to Puerto Rico's fertility decline. There was an increase between 1960 and 1970 in the proportions of single women at all ages. In addition, the proportion of ever-married women using oral contraceptives grew from 11 percent in 1968 to 20 percent in 1974. This increase compensated for small reductions in the prevalence of sterilization; the overall level of contraceptive use remained at almost exactly the same level between 1968 and 1974-about 60 percent. A third factor which may have contributed to the reduction in Puerto Rican fertility since 1950 is abortion. The practice of abortion there remains within a legal gray area, however. Technically, abortion in Puerto Rico has been legal since the U.S. Supreme Court decisions of 1973. However, local laws which forbid abortion except on medical indications are currently being enforced, and abortion is practiced as if it were illegal. For this reason, the prevalence of induced abortion can only be estimated; some observers estimate that there are currently 15,00018,000 abortions performed annually in Puerto Rico.