This article explores the dynamics of languages in markets in Senegal. Using the examples of Sor and Ndar Toute markets in Saint-Louis, this study highlights the multiple factors influencing language use. In fact, being a place of trade, Saint-Louis’ central and district markets are frequented everyday by people coming from different places, not sharing the same beliefs and culturally different. This sociolinguistic situation has many consequences on language use. In this project, I try to investigate into language use in the market areas of Sor and Ndar Toute in Saint- Louis. It will be concerned about reflecting on the living experiences of traders and customers in these markets and show how this fact is determinant to languages that are most representative there, just to say how each language influence the other. This work finally highlights the crucial role played by sellers and buyers in the promotion of languages particularly the local ones.