Contraception, considered as the ultimate in preventive medicine, is discussed from the viewpoint of the child, the mother and society, then methods are compared in this context. Congenital and hereditary disorders have doubled since 1916, while infant mortality from malnutrition and infections has fallen from 24.1 to .6/1000. Unplanned children, such as products of a refused abortion, youngest in a large family, firstborn in a young marriage and illegitimate children, suffer increased risks of mental illness, delinquency and infant mortality, in various studies. Adoption is not the solution since most children in foster care are too old to be desirable for adoption; 33-60% of these have emotional problems. Battered children, a phenomenon discovered by the medical profession in 1961, are often undesired children. In the author's view, pregnancy, although a natural function, represents consid erable danger to a woman's health, particularly if she is under 20. As evidence for this view she states that before prenatal care and hospital deliveries were universal, maternal mortality was 4.5%, and it is 10-12% in some developing countries. Socially, an unwanted pregnancy can be disastrous, particularly if a young woman is forced to marry or stop her education. On a societal level, poverty is prepetuated where contraception is not available. In U.S.A. in 1962 50% of families making less than $3000/year had 4 or more children, compared to 25% of those making $10,000 or more. These children have contributed disproportionally to societal costs, e.g., social services and uncontrolled urbanization, even in the U.S. and Canada. The benefit-cost ratio of providing contraception was estimated in England in 1971 as 20/1 to 128/1. The author recommended the specific contraceptive methods: pills especially for adolescents and menopausal women, copper IUD for those who cannot use pills, chemical and barrier methods combined for special cases, vasectomy and abortion where applicable.