I modify Grice's theory of conversational implicature so as to accommodate acts of implicating propositions by asking questions, acts of implicating questions by asserting propositions, and acts of implicating questions by asking questions. I describe the relations between a declarative sentence's semantic content (the proposition it semantically expresses), on the one hand, and the propositions that a speaker locutes, asserts, and implicates by uttering that sentence, on the other. I discuss analogous relations between an interrogative sentence's semantic content (the question (...) it semantically expresses), and the questions that a speaker locutes, asks, and implicates by uttering that sentence. (shrink)