No one would dispute that Mixtec languages are tonal. However, little or no research has been done on the relationship between tone association and prosodic constituents. This paper presents data to show 1) the complex tone system of Nuxaá Mixtec, 2) evidence for foot structure, and 3) preliminary data which show that there are both tonal and durational differences depending on whether the words under consideration belong to the same prosodic constituent or not.