This study is the first acoustic analysis of voice quality in the two main ethnic dialects of New Zealand English. In a production experiment, narratives from 36 speakers were analyzed and H1-H2 spectral tilt measures were calculated for each vowel. The results provide instrumental evidence for impressionistic claims about the differing voice quality features of the two main ethnic groups, showing that Maori English speakers are creakier than European New Zealanders. A perception experiment was also carried out to determine the perceptual salience of voice quality for the identification of speaker ethnicity. The results of regression analyses confirm that listeners are sensitive to the phonation differences, and are able to rely on phonation cues in an ethnic dialect identification task. The study demonstrates the role of voice quality as a critical sociolinguistic variable, and highlights the importance of listeners' previous dialect exposure in terms of sensitivity to prosodic cues.