Standard semantic theories of indefinite descriptions, including both those that analyze them as inherently existentially quantified and those that analyze them as non-quantificational, variable-contributing elements , predict that indefinites always have existential force if outside the scope of any operator, that they assert rather than presuppose existence, and that they are not essentially context-sensitive. In this work the author shows that bare plural indefinite descriptions in English, in one of their readings, do not have existential force, that even in the absence of any operator, they presuppose rather than assert existence, and that they are crucially context-sensitive. This reading, called the called the "functional reading," is argued to constitute a distinct interpretation that cannot be subsumed under the regular generic or existential interpretation. The author develops an analysis that captures the similarities and differences between indefinites with the functional reading and definites within the framework of dynamic semantics. The universal quantificational force, the existential presupposition, and the context-sensitivity associated with the functional reading follow from the felicity conditions. Bare plural indefinite descriptions are associated with and general principles governing informational accommodation and contextually salient functions invoked to guarantee felicity.More generally, this work can be seen as an argument in favor of (i) a dynamic theory of meaning, as opposed to the classical truth-conditional theory; (ii) a presuppositional analysis of descriptions; and (iii) a strong interaction between semantics and pragmatics, whereby background knowledge directly affects interpretation in a way that cannot be factored away as a Gricean effect.