Based on fertility surveys conducted in seven Latin American cities, this study examines the proposition that the crucial variable determining the relationship between maternal employment and fertility may be the extent of incompatibility between joint occupancy of the roles of mother and worker. Where these two roles are incompatible, female employees should have fewer children than the nonemployed. Two structural aspects of role incompatibility (employment outside the home and white collar employment) are related to fertility in most cities. The number of hours employed outside the home is usually unrelated to fertility. Many of the relationships are simply due to more education and greater approval of nondomestic activities among employed wives. The wife's motivation for employment, her education, and her preferred role seem to exert greater influence on her fertility than her actual role of employee or homemaker. A significant finding of the research is the role of individual city and the ecological conditions operative within each.