This paper addresses the meaning and use of clefted wh-interrogatives (I-clefts) in Swedish. It is shown that I-clefts always relate immediately to the topic under discussion and serve to clarify a matter in relation to this topic. They are never used in out-of-the-blue contexts. I argue that I-clefts have the same information structure as typically assumed for declarative clefts: the clefted clause expresses an existential presupposition and the cleft phrase is the identificational focus of the utterance. I further argue that the implication of existence commonly associated with canonical argument questions is weaker (a conversational implicature) than the existential presupposition associated with clefts. The results from an extensive corpus survey show that argument I-clefts (who, what) constitute no less than 98% of the total number of I-clefts in my material. This frequency is linked to the presuppositional status of the cleft construction: in contexts where the denoted event is presupposed as part of the common ground, the clefted variety is the more effective choice, due to its clear partitioning of focus and ground. The ‘cost’ of using a more complex syntactic structure (the cleft) is thus counterbalanced by the benefit of being able to pose a question adjusted to the contextual requirements. As non-argument questions are typically presuppositional irrespective of syntactic form, the gain of using a cleft is less obvious – hence their infrequency in the material.