Objective. To describe the rationale and the method­ology of a multicenter project to study the etiology of breast cancer in young Latin American women. Materials and methods. The International Agency for Research on Cancer has established an international collaborative population-based case-control study in four countries in Latin America: Chile, Colombia, Costa Rica, and Mexico (the PRECAMA study). Standardized methodologies were developed to collect information on reproductive variables, lifestyle, anthropometry, diet, clinical and pathological data, and biological specimens. The study will be extended to other countries in the region. Conclusion. PRECAMA is unique in its multidisciplinary approach that combines genet­ics, genomics, and metabolomics with lifestyle factors. The data generated through this project will be instrumental to identify major risk factors for molecular subtypes of breast cancer in young women, which will be important for pre­vention and targeted screening programs in Latin America.