Two experiments explored discourse and communicative factors that contribute to the perceived prominence of a word in an utterance, and how that prominence is realized acoustically. In Experiment 1 two hypotheses were tested: (1) acoustic prominence is a product of the given-new status of a word and (2) acoustic prominence depends on the degree to which a referent is accessible, where greater acoustic prominence is used for less accessible entities. In a referential communication task, speakers used acoustic prominence to indicate referent accessibility change, independent of givennew status. In Experiment 2 a variant of Tic Tac Toe was used to investigate whether effects of accessibility are driven by a need to signal the importance of a word or to indicate the word’s predictability. The results indicate that both importance and predictability contribute to the prominence of a word, but in different ways.