L O Adéwọlé, Obáfé̩mi Awólọ́wò̩ University Studies on Yorùbá have typically ignored or undervalued the place of word structure within a generative grammar. This neglect has a far reaching effect on the study of the language first, because words are the basic units in the description of any language and second, because the Yorùbá word structure offers a microcosm of some of the descriptive problems of sentences in the language. In this paper, therefore, we shall take a critical look at the notion, head, in the Yorùbá morphology within a variant of the Generalised Phrase Structure Grammar (GPSG henceforth) developed by Cann (1986).