Communication theories and research data were used to design cross-cultural health education messages. A University of California Los Angeles-Universidad Autonoma in Tijuana, Mexico, research team used the methods of ethnographic and survey research to study behaviors, attitudes, and knowledge concerning prenatal care of a sample of pregnant low-income women living in Tijuana. This audience provided information that served as a framework for a series of messages to increase awareness and change prenatal care behaviors. The message design process was guided by persuasion theories that included Petty and Caccioppos elaboration likelihood model, McGuires persuasion matrix, and Banduras social learning theory. The results from the research showed that poor women in Tijuana tend to delay or not seek prenatal care. They were not aware of symptoms that could warn of pregnancy complications. Their responses also revealed pregnant womens culturally specific beliefs and behaviors regarding pregnancy. After examination of these and other results from the study, prenatal care messages about four topics were identified as the most relevant to communicate to this audience: health services use, the mothers weight gain, nutrition and anemia, and symptoms of high-risk complications during pregnancy. A poster, a calendar, a brochure, and two radio songs were produced and pretested in focus groups with low-income women in Tijuana. Each medium included one or more messages addressing informational, attitudinal, or behavioral needs, or all three, of the target population.