Identified Costellariidae species from Mozambique are listed, along with the description of 10 new species. The type locality of Thala adamsi and Mitra clathrata has been defined. A neotype for Voluta mucronata has been selected and Mitra nigricans Dautzenberg & Bouge, 1923 is renamed Vexillum nigripulchrum. The type locality of Mitra praetexta has been designated. Notes on the natural history of Mozambique are followed by a historical outline of the occurence of the family Costellariidae.