Consensual unions are a well-known practice among the lower social strata in Latin America. However, this type of union is increasing in the region, among higher educated groups and in countries where they were never widespread, such as in Brazil. This study uses couples' data from the demographic census available at IPUMS (N=193,689) to identify the socioeconomic and cultural features of consensual unions in Brazil. The effects of women's education, couples' income, children, and religion on nuptial behavior are analyzed. Utilizing logistic multilevel analysis, special attention is paid to the effect of differences in the cultural environment of states in the five major regions in which these unions occur. Results indicate that socioeconomic factors affect the incidence of consensual unions in Brazil. Consensual unions are more common among lower income couples and less educated women, but are also found among the upper classes. Cultural diversity between Brazilian states is also reflected in nuptial behavior. Significant variance at the state level is partially explained by the ethnic composition of each state.