The intelligibility of nonnative English-speaking teaching assistants (NNSTAs) is an issue that concerns researchers, administrators, teacher-trainers, and undergraduates. Based primarily on the work by Smith & Nelson (1985), this paper offers a novel method of looking at intelligibility—first recording undergraduates' immediate feedback on communication breakdowns while watching three NNSTA presentations, then following with an analysis of those communication break downs by a group of ESL specialists. The analysis in this study yielded a taxonomy offactors affecting the intelligibility of the NNSTAs. This study also found pronunciation to be the main cause of unintellgibility in the three NNSTA presentations, whether in isolation or in combination with vocabulary misuse, nonnative speech flow, or poor clarity of speech, a finding which confirms students' perceptions of the language problems of NNSTAs reported by Hinofotis & Bailey (1981) and by Rubin & Smith (1989).