From the seminal work by Aronoff (1994), the study of inflectional classes has become of interest in morphological theory. Most of our current knowledge of verb inflectional classes, also known as “conjugation classes”, remains circumscribed to European languages. On the other hand, the Oto-Manguean languages of Mexico have recently awoken interest because of their puzzling internal diversity and morphological abundance, but much of their morphological complexities remain poorly understood because of the lack of comprehensive materials. To increase our understanding of such classes, in this article I present an analysis of the three conjugation classes of Tilapa Otomi, an Otomian language close to extinction which belongs to the Oto-Pamean branch of Oto-Manguean. In the article, I also provide an example of how the canonicity of conjugation classes can be ranked following the approach advocated by Corbett (2009). The results of such an evaluation show that while two of the three classes of Tilapa Otomi are canonical to a certain extent, a third one is a very poor example of an inflectional class for the purposes of typological comparison.