Relevance-Based Partition Semantics for Why-Questions Jonathan Shaheen Abstract: This work argues that partition semantics can be extended to cover why-questions and their answers, and then develops such an extension. Building on Jeroen Groenendijk’s Logic of Interrogation and incorporating a theory of why-questions initially put forward by Bas van Fraassen, it provides a unified notion of contextual answerhood for both why-questions and constituent questions. Non-constructive and constructive versions of the semantics are indicated, their meta-logical features are briefly explored, and two applications for the semantics are described.