Contemporary grammars now admit that for many "'être ' verbs", 'avoir' is used as well, variously attributing the alternation to semantic, syntactic and/or stylistic distinctions. Sankoff and Thibault (1980, 1997), Canale et al. (1978) and Russo and Roberts (1999) confirm that variable 'avoir' usage in Montreal, Welland and Sudbury and Vermont French respectively, is conditioned by such factors. In this thesis I extend the analysis of 'avoir'/' être' variation to another variety of North-American French. From the speech of 45 informants selected from the Ottawa-Hull French Corpus (Poplack, 1989), I extracted every token of every verb admitting auxiliary variation, distributed across 21 verbs. Each of these was coded for a number of linguistic and non-linguistic factors hypothesized to affect variability in auxiliary choice. Some replicate those used in the earlier studies. Others are operationalizations of factors suggested to favour 'avoir' use over the course of the development of the French language including type of complement if any, and whether the verb was also used reflexively. (Abstract shortened by UMI.)