In this study we explore listeners' sensitivity to vowel to vowel (VV) coarticulation, using both event-related potential (ERP) and behavioral methodologies. The stimuli used were vowels "colored" by the coarticulatory influence of other vowels across one, three or five intervening segments. The paradigm used in the ERP portion of the study was intended to elicit the mismatch-negativity (MMN) component, a negative deflection typically seen at central midline scalp sites about 200 ms after the presentation of a "deviant" acoustic stimulus occurring among a train of "standard" acoustic stimuli. VV coarticulation at near and medium distances was associated with significant MMN-like effects, which however were not observed in response to the longest distance coarticulatory contrasts. Subjects' ERP results did not predict their performance on the behavioral task, which found evidence of listener sensitivity to even the furthest distance coarticulatory effects. Although the MMN has previously been shown to be sensitive to phonemic contrasts, this is the first study using ERP methodology to investigate the subphonemic processing associated with the perception of coarticulation.