This paper shows how to represent actions on belief (such as deducing and evaluating) in a language in which it is also possible to represent actions on the world (such as putting one block on top of another). It is done by combining modal logics of belief and of action in such a way that actions on belief can be represented as perfectly respectable modals with standard and well-motivated semantics, obeying sensible rules. One basic actions is proposed, representing finding that a fact S is true; it has a variant, representing finding that S is true given a fact (or theory) T. These can be used to define other, more usable, actions: finding whether S, finding an object with property ø, and evaluating a term.