The International Institute for the Portuguese Language, under the auspices of the Community of Portuguese Speaking Countries, is coordinating the development of the Common Orthographic Vocabulary (VOC). VOC will be a large on-line lexical database which will take into account the varieties of the eight Portuguese speaking countries (Angola, Brazil, Cape Verde, Guinea-Bissau, Mozambique, Portugal, Sao Tome and Principe, and East Timor). The project comprises two inter-related phases: 1) the merging of existing Portuguese and Brazilian vocabularies as an evidence of the lexicographic tradition; 2) the compilation of corpora for the development of national vocabularies for the remaining countries. This paper describes in detail the methodology of the tasked being pursued in the context of that project.