This study examined the discrimination of word-final stop contrasts (/p/-/t/, /p/-/k/, /t/-/k/) in English and Thai by 13 native speakers of Cantonese[C]. The C participants' discrimination accuracy was compared to the results previously obtained from two groups of 18 participants (Australian English [AE], Thai [T] in order to assess the influence of first language (Ll) on cross-language speech perception. The second aim was to examine how difference in familiarity with stimulus languages might affect the C participants' discrimination of stop contrasts. Word-final stops in Cantonese and Thai are unreleased whereas they may be released in English. This may enable the C participants to discriminate Thai final stops more accurately than the AE participants, but a lack of familiarity with Thai may keep them from reaching their optimal discrimination accuracy. A discrimination test with an oddity design was used to test participants' discrimination of stop contrasts. The C group did not show an advantage over the AE group and both groups were clearly less accurate than the T group in discriminating the Thai contrasts. However, all three groups were highly accurate in discriminating the English contrasts. These findings suggest that experience with specific (i.e., unreleased final stops) and native phonetic realization of sounds may be essential in accurate discrimination of stop contrasts.