PIP: Data examined in this study are from the 1976 Mexican Fertility Survey. The authors review previous findings and compare information from this survey with data from the 1969 PECFAL Survey. They then examine the types of consensual union and factors such as women's age, educational status, occupation, premarital fertility, and rural or urban residence. The focus of the study is on the extent to which consensual unions eventually become legal marriages. The authors also investigate the increasing probability of termination of marriage through divorce or separation, especially in urban areas.