This article reports on the design and implementation of a prenatal outreach and education intervention for low income, Hispanic women living in three migrant and seasonal farmworker communities in Arizona. The program included three major elements: a Spanish language prenatal curriculum; a group of mature Hispanic women recruited from the target communities and trained as "Comienzo Sano" (healthy beginning) Promotoras (health promoters), and the organization of a support network of local health professionals. The rationale for the demonstration is reviewed, and the structure of the intervention is described. Factors which facilitated and constrained implementation of the program are identified, and guidelines are provided for other health care providers and health educators interested in developing similar programs.