Most verbs in Zenzontepec Chatino fall into one of seven inflectional classes according to which allomorphs of the aspect/mood prefixes they occur with (Campbell 2011), and they also fall into one of nine tone alternation patterns across the different inflectional categories. The intersection of these two layers of inflection, and some further irregularities within them, yields 39 distinct prefix-tone classes. Some of the prefix-tone classes are well populated, while others have only a few or even just one verb in them. Meanwhile, there are another 29 irregular verbs in the language that have either some stem suppletion or some exceptional prefixal inflection, bringing the number of distinct inflectional patterns up to 68. There are only 378 basic verbs that fall into these 68 inflectional patterns. The layered complexity of aspect/mood inflection, with the large number of small, even singleton, classes that it creates, blurs the line between inflectional classes and irregular verbs. While it makes sense to consider the more frequent patterns as inflectional classes, the less frequent patterns might just as well be considered irregular verbs instead of very small inflectional classes. Ultimately, there is no clear choice of exactly where such a line should be drawn between inflectional classes and irregular verbs, and Zenzontepec Chatino verbal inflection raises interesting and challenging questions for morphological typology.