Ernestina took part in the flow of rural to urban migrants so common in Mexico since the second World War: she had been born on a rancho (unincorporated rural settlement) in Chihuahua and moved first to a nearby town and then to Mexico City to work as a domestic servant, and then migrated with her husband and family to various centers in Baja California, on the U.S.-Mexico border. She was one of the urban poor in Mexican cities who invaded lands and self-built housing in order to have a roof over their heads, while raising her eight children. She worked in the informal and formal economies in Mexico and as a domestic servant in the United States. As president from 1985 to 1992 of the squatter settlement where she lives, Ernestina was involved in political maneuverings and demonstrations to assure herself and her fellow community residents of property rights and urban services such as electricity, running water, and sewerage. She confronted many dangers in the colonias (named urban neighborhoods) in Mexicali where she lived and lives, and in two others she helped to invade. In her private life she suffered under the reign of machismo, with an unfaithful and physically and emotionally abusive husband. Her story would be valuable to those who study social movements and/or the position of women in Mexico.