Previous research suggests that English monolingual children and adults can use speech disfluencies (e.g., "uh") to predict that a speaker will name a novel object. To understand the origins of this ability, we tested 48 32-month-old children (monolingual English, monolingual French, bilingual English-French; Study 1) and 16 adults (bilingual English-French; Study 2). Our design leveraged the distinct realizations of English ("uh") versus French ("euh") disfluencies. In a preferential-looking paradigm, participants saw familiar-novel object pairs (e.g., "doll-rel"), labeled in either Fluent ("Look at the doll/rel!"), Disfluent Language-consistent ("Look at 'thee uh' doll/rel!"), or Disfluent Language-inconsistent ("Look at 'thee euh' doll/rel!") sentences. All participants looked more at the novel object when hearing disfluencies, irrespective of their phonetic realization. These results suggest that listeners from different language backgrounds harness disfluencies to comprehend day-to-day speech, possibly by attending to their lengthening as a signal of speaker uncertainty. Stimuli and data are available at <https://osf.io/qn6px/>.