The Obligatory Contour Principle (OCP), originally proposed to account for the distribution of tones in West African languages (see Leben 1973; Goldsmith 1976), has been extended to a wider range of phenomena, leading to McCarthy's formal definition of the principle: “At the melodic level, adjacent identical elements are not permitted” (1986:208). The study of Arabic phonology and morphology has had a profound influence in extending the role of the OCP in grammar. The OCP, as first proposed, is illustrated by the tonology of Mende, which has surface tone patterns LHH and HLL (H hi…