The dramatic increase in the use of pesticides has led to increasing political, social, human health, and environmental concerns. Accidents due to misuse among users have risen dramatically and speak to the need for the development of practical and useful communication programs and materials, particularly with small farmers. Three studies were designed to research and test the comprehensibility of sets of pictographs, pictures, and symbols depicting proper and improper procedures for using agricultural pesticides. Field testing was conducted with Mexican farm workers in California and small farmers and farm workers inEcuadorSouth America. Results indicate that, like language, the meaning of symbols and visual literacy will have to be taught if the goal of perfect comprehensibility is to be achieved. Furthermore, research on visual communication materials and information systems in this area must become an integral part of formal and nonformal educational efforts. These efforts must be undertaken not only by communication researchers but also in conjunction with technical personnel.