IN the three years from 1967 to 1970, a revolution has occurred in the abortion laws and practices in the United States. That revolution is still in process. Our once highly restrictive antiabortion laws have been reformed in 13 states and virtually repealed in four states. No other country has a statute which explicitly makes abortion a matter for decision by the woman and her physician. Although other countries permit abortion on request of the woman under certain circumstances, the four American states have pioneered in treating abortion, as a matter of law, like any other medical procedure. As a result of recent developments, the United States has become a laboratory in which three different types of legal regulation of abortion can be compared and evaluated. We can also profit from the longer experience of other countries with abortion statutes of varying liberality, although account must be taken of differing family planning programs and systems of delivering health services.