Purpose: The purpose of this study was to examine the intelligibility of English consonants and vowels produced by Chinese-native (CN), and Korean-native (KN) students enrolled in American universities. Method: 16 English-native (EN), 32 CN, and 32 KN speakers participated in this study. The intelligibility of 16 American English consonants and 16 vowels spoken by native and nonnative speakers of English was evaluated by EN listeners. All nonnative speakers also completed a survey of their language backgrounds. Results: Although the intelligibility of consonants and diphthongs for nonnative speakers was comparable to that of native speakers, the intelligibility of monophthongs was significantly lower for CN and KN speakers than for EN speakers. Sociolinguistic factors such as the age of arrival in the United States and daily use of English, as well as a linguistic factor, difference in vowel space between native (L1) and nonnative (L2) language, partially contributed to vowel intelligibility for CN and KN groups. There was no significant correlation between the length of U.S. residency and phoneme intelligibility. Conclusion: Results indicated that the major difficulty in phonemic production in English for Chinese and Korean speakers is with vowels rather than consonants. This might be useful for developing training methods to improve English intelligibility for foreign students in the United States.