This study investigated U.S. undergraduates' perceptions of non-native speakers' (NNS) speech which had received 100% proficiency scores on the TOEFL iBT test. Fifty-five U.S. undergraduates rated 20 speech samples for comprehensibility, accentedness, and acceptability. The speech samples were also analyzed for acoustic fluency. Descriptively, although all NNSs had been certified as highly proficient by the high-stakes test raters, U.S. undergraduates perceived them to be heavily accented, not perfectly comprehensible, and not completely acceptable as a teacher and as a peer. Multiple regression analyses showed that comprehensibility significantly predicted high proficiency NNSs' acceptability as a teacher and as a peer whereas accentedness did not. Additionally, syllables per second emerged as the strongest predictor of NNSs' comprehensibility and accentedness whereas mean length of run emerged as the strongest predictor of NNSs' acceptability. These findings suggest that obtaining competitive scores on the speaking component of the high stakes test may not sufficiently guarantee NNSs' acceptability for teaching and group activities in U.S. academic contexts.