This paper examines presupposition and implication from a semiotic perspective. It suggests that the conventional approaches to presupposition have a limited focus because of emphasis on truth-value, or the propositional level of the utterance. The paper demonstrates how texts construct an assumed world of agents, which can be traced in narrative structure. This 'presupposed world' gives the story the form in which it is narrated. By analyzing utterances from a variety of written texts, the paper outlines an approach that traces presupposed worlds in syntactic and semantic strategies. The paradigmatic and syntagmatic axes, and the deictic framework of the text are examined to show this. The paper concludes by discussing the significance of presupposed worlds for semiotic text analysis.