The present study applies corpus-based methods to document the distributional patterns of previously reported lexical bundle functions as they relate to discourse structure. Specifically, 84 lexical bundles and their discourse functions (Biber "et al." 2004a) were tracked in 1,176 discourse units extracted from the initial phases of 196 university class sessions. The findings show that in the opening phase of class sessions bundles conveying stance are most frequent while bundles articulating reference are least in number. With the start of the instructional phase, however, stance bundles sharply drop and referential bundles start rising. Discourse organizing bundles are least prominent overall, although with some rise at the very beginning of the instructional phase. These findings indicate that lexical bundle functions correspond well to the communicative functions in discourse structure found through linguistic variation (Csomay 2005) and suggest that there is a strong relationship between grammar and lexis on the discourse level.