This thesis examines the decline of the pass simple and the concurrent rise of the pass compos across three periods of Classical French, a change which is typically treated as a case of grammaticalization. This study is based on a quantification of variable contexts through the construction and examination of historic corpora comprised of two different text types: letters and essays. Ultimately, the goal of this study is to provide concrete information on the diachrony of the opposition between the pass simple and the pass compos through a statistical analysis of the factors that influenced their use during the time periods in question. Factors analyzed in this study are text-type, temporal and adverbial reference, Aktionsart (lexical aspect), semantic class, object plurality, clause type, grammatical person, and negation. Diachronically, the multivariate analyses indicate an increasing restriction on the factors that favored the pass simple over the pass compose.