This chapter considers how Wolof, an Atlantic language spoken in Senegal, has become an important lingua franca, and how French has contributed to the ascent of Wolof. The nature of social relations between Africans and French in cities along the Atlantic coast in the 18th and 19th centuries were such that a prestigious urban way of speaking Wolof that made liberal use of French borrowings became the language of the city. As an index of urban belonging, opportunity, and modernity, Wolof was viewed as a useful language, a trend that has continued up to the present. Four case studies illustrate how the use of Wolof facilitates mobility for speakers of other languages in Senegal. By drawing a distinction between the formal and informal language sectors, this chapter offers a more realistic view of everyday language practices in Senegal, where Wolof is the dominant language.