Considers the association of cohabitation experience with externalizing behavior among children of Latina mothers whose ethnic origin is in Mexico, Puerto Rico, or the Dominican Republic. Children of Mexican-origin mothers had greater externalizing problems in childhood and adolescence when their mothers were born in the United States or had immigrated as minors. For children of Caribbean-origin mothers, being born to a cohabiting or married mother had a statistically equivalent association with externalizing behavior when mothers were born outside the mainland United States (Dominican and island-born Puerto Rican mothers). Children of mainland-born Puerto Rican mothers had more behavior problems when their mothers cohabited at birth.