Neural tube defects (NTDs) are serious birth defects of the brain and spine that affect approximately 3,000 pregnancies in the United States each year and affected 404 pregnancies in Puerto Rico from 1996 to 2002. Consuming the B vitamin folic acid can reduce the incidence of NTDs 50%-70%, and recent efforts to reduce NTD rates have focused on increasing the number of childbearing-aged women who take a vitamin containing folic acid every day. As the first stage of formative research in campaign planning, two exploratory, qualitative studies were conducted in order to (a) understand the complexity of vitamin use among women in the United States and Puerto Rico and (b) serve as a foundation on which to develop national communication and education interventions. Also, this information shed light on theories that might be used to guide campaign development. Results indicated that campaign messages designed to increase folic acid use through multivitamin supplementation in the United States must address women's barriers to vitamin use (e.g., cost, time), increase women's perceived need for multivitamins (e.g., identify immediate, tangible results from taking a daily multivitamin), and address the relationship between daily food choices and the need for supplementation. Future campaign messages in Puerto Rico must focus on many of these same issues, in addition to increasing women's knowledge about when folic acid should be taken in relation to pregnancy and addressing women's perceptions that vitamins cause weight gain (an undesirable outcome for most participants). The practical and theoretical implications of these results are discussed in terms of their contribution to the development of a creative new approach to increase multivitamin consumption among women of childbearing age in the United States and Puerto Rico.