This is a contrastive study of focus and topicalisation within the framework of Culioli's theory of enunciation, based on the concepts of preconstruct and assertion. Topicalisation is characterised as the articulation between a topic and a rheme. The topic is the singled out, initial term of a speech unit. It supports the predication that follows, called the rheme. Focus consists in the imbrication of two propositions within a single speech unit : a predicative relation and the identification of one term of this predicative relation, the focused term. What is asserted is the identification of the focused term, while the predicative relation is given the status of a preconstruct. The study of these phenomena in the languages of sub-Saharan A...