Workers in Mexico's maquiladoras (assembly plants) are mainly young, single women, many of whom could benefit from emergency contraceptive pills (ECPs). Because ECPs are readily available in Mexico, women who know about the therapy can obtain it easily. Do maquiladora workers know about the method? Could worksite programs help increase awareness? To investigate these questions, we conducted a five-month intervention during which workers in three maquiladoras along the Mexico-United States border could attend educational talks on ECPs, receive pamphlets, and obtain kits containing EC supplies. Among the workers exposed to our intervention, knowledge of ECPs increased. Reported ECP use also increased. Although our intervention apparently increased workers’ knowledge and use, the factory proved to be a difficult intervention setting. Problems we experienced included a factory closure and management/staff opposition to certain project elements. Future studies should continue to investigate work-site interventions and other strategies to reach workers.