This paper discusses three potential varieties of update: updates to the common ground, structuring updates, and updates that introduce discourse referents. These different types of update are used to model different aspects of natural language phenomena. Not-at-issue information directly updates the common ground. The illocutionary mood of a sentence structures the context. Other updates introduce discourse referents of various types, including propositional discourse referents for at-issue information. Distinguishing these types of update allows a unified treatment of a broad range of (...) phenomena, including the grammatical evidentials found in Cheyenne (Algonquian) as well as English evidential parentheticals, appositives, and mood marking. An update semantics that can formalize all of these varieties of update is given, integrating the different kinds of semantic contributions into a single representation of meaning. (shrink)