The early focus of the Ethnologue was on L1 use and is reflected in the maps that are included with each new edition. Typically, the maps show locations and boundaries corresponding to the distribution of L1 speakers. The location of widespread, second, or additional languages (such as national languages, lingua francas, and languages of wider communication) is only occasionally represented by maps, using a variety of methods. Major factors affecting this effort are related to language identification (ISO 639-3), categorization (status: sociohistorical, official recognition, vitality), and analytical and research methods (lexical similarity, intelligibility, bilingual proficiency). This chapter examines the Ethnologue’s approach in all of these areas. Currently, significant effort is being made to structure the Ethnologue database to provide expanded data on the ecological setting of each language. This should significantly increase capacity for mapping the use of widespread L2s. A sample map showing the use of Lingala/Bangala is provided.