I argue that non-declarative utterances communicate propositional information about the speaker’s state of mind. Non-declarative utterances include utterances of the non-declarative clause types, i.e., interrogatives, imperatives, and exclamatives, as well as utterances of exclamations and interjections such as “wow,” “sh,” “thanks,” “argh,” “oops.” I argue that such utterances involve a proposal to make it common ground that the speaker has a particular kind of attitude. This implies a view on which a non-declarative utterance is insincere when the speaker does not have the relevant attitude. I apply this view to indirect speech acts involving non-declaratives. Finally, to account for non-sentential exclamations and interjections, I propose a view of when such utterances are communicative acts and suggest that only communicative acts are evaluable as insincere or not.