Listeners perceptually assimilate nonnative phones to native phonemes, but do they do so with unfam-iliar accents of their own language? We assessed Australian (Aus) listeners’ assimilation of vowels in two unfamiliar English accents, and whether prior short-term exposure to the other accent would yield any adaptation to its vowels. Participants categorized the vowels of nonce words spoken in Aus or one of the unfamiliar accents (London [Lon]; Yorkshire [Yks]), after first hearing a story told round-robin by multiple speakers of Aus or of the other accent. Here we address six vowels with differing assimilation predictions for Lon vs. Yks. Results indicate that perceptual assimilation does contribute to perception of vowel variation, and that brief exposure to an unfamiliar accent can yield some degree of adaptation to its vowels. Keywords: vowel perception, English accents, perceptual assimilation, accent adaptation