We consider 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. Data were drawn from three waves of the Three-City Study (N = 656 mother-child pairs). 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.