Most Romance languages have reduced the Latin conjugation classes (CCs) maintaining only three main classes which are marked as general rule by different theme vowels (ThVs). The development in French, however, is different and has led to less transparent verbal forms and to a CC system that is not describable, at first glance, in terms of ThVs. In our contribution, we pursue the following questions: Does French have ThVs? And if so, which form do the French theme “vowels” – or maybe better, theme extensions – have? Can French verbs be segmented in more than two constituents? Based on a critical discussion of psycholinguistic evidence and embedded in the framework of Distributed Morphology, we show that, in French, regular verbs, verbs with morphophonologically predictable allomorphy and even idiosyncratic verbs are decomposed for lexical access. We argue for two thematic CCs (with the ThV [-ə-] for the 1st CC of the type aimer and [-is-] for the CC of the type finir), while the remaining CCs are athematic. Certain types of root allomorphy, e.g. the (non)appearance of root final consonants, depend, in essence, on whether or not there is a ThV-position available. We propose a feature hierarchy for French CCs, which additionally mirrors the fact that even athematic CCs can have ThVs in certain neutralization contexts, where the realization of the ThV is taken over from the CC of the type finir.