On the face of it, Lara's statement is not an answer to Carol's question. Lara doesn't say Yes or No. Yet Carol will immediately interpret the statement as meaning"No" or"Probably not." How can we account for this ability to grasp one meaning from a sentence that, in a literal sense, means something else? It seems to depend, at least partially, on the assumption that Lara is being relevant and informative, adhering to the maxims of Relation and Quantity. (To appreciate this point, try to imagine Carol's reaction if Lara had said something like Roses are red, you know. Given that Lara's original answer contains relevant information, Carol can work out that"exam tomor row" conventionally involves"study tonight," and"study tonight" precludes"party tonight." Thus, Lara's answer is not simply a statement about tomorrow's activities, it contains an implicature an additional conveyed meaning) concerning tonight's activities. It is noticeable that, in order to describe the conversational implicature involved in Lara's statement, we had to appeal to some background knowledge(about exams, studying and partying) that must be shared by the conversational participants. Investigating how we use our background knowledge to arrive at interpretations of