The position taken in this paper is that the sentence adverb should be viewed not as an occurrence within a sentence but as a kind of illocutionary force marker of a speech art. Three points are argued in the paper: (1) that current linguistic analyses of sentence adverbs are inadequate even to the purposes of the analysts; (2) that treating sentence adverbs as illocutionary speech acts--more precisely, as illocutionary force markers of propositions--will produce an explanatory model meeting the needs of both linguistic analysts and speech act theorists; and (3) that this explanatory model may be profitably adapted to other language problem areas. The paper also suggests a theoretical connection with conversation analysis. Categories of sentence adverbs/illocutionary force markers are offered, as are their essential conditions. (RL)