At the end of the 1960s, living as a couple was hardly conceivable outside of marriage. Today, however, unmarried couples freely live together. The nature of unions has changed dramatically over the course of 20 years. Marriage is losing its status as a definer of couples at the same time as in most Western European countries, the birth rate among unmarried couples is rising more or less rapidly. The proportion of births outside of marriage in Switzerland grew slightly over 20 years from 4% in 1970 to 6% in 1990. The proportion reached 8% in 1997. Data from a study of families are used to describe changes in the associations between marital and reproductive behaviors. Since children born outside of marriage usually remain with their mothers, this study addresses a sample of only women. The government study was conducted between October 1994 and May 1995, involving 3881 women and 2083 men born between 1945 and 1975. The acquired potential for women to more freely practice their sexuality while effectively controlling their fertility contributed to the development of cohabitation outside of marriage. However, unmarried, cohabiting couples tend to abstain from childbearing because of a certain Swiss traditionalism regarding notions of what comprises a family and legislation which is particularly unfavorable to unmarried parents and their children.