Proto-Southern had three classes of verb - two thematic vowel classes, where inflected forms contained a stem vowel (either a or i), and athematic verbs, where the verb root ended in a vowel and inflectional endings were applied directly to the root. There are a number of irregular verbs which appear to have come from even earlier consonant-stem verbs, but these fall outside the three main paradigmatic classes.

Proto-Southern verbs were inflected for four moods - indicative, subjunctive, optiative, and negative - and three aspects - imperfective, perfective, and habitual - although not all combinations of aspect and mood have distinct phonological forms. The indicative and negative moods also distinguished past and nonpast tense on the verb. A variety of other modalities and tenses, as well as a passive voice, are indicated with auxiliary verbs.

The citation form of a verb is its infinitive, which is regularly formed by adding the suffix -ru to the stem vowel or directly to the root in the regular verb paradigms. Verb infinitives could take a limited number of case endings, and there was no other non-finite form of a verb. Participial forms of verbs in Proto-Southern's daughter languages generally developed from the infinitive inflected for one case or another.

Indicative mood

Three regular verbs will be used in the following sections to illustrate the three regular paradigms. For a-thematic verbs, misa-ru, "to see"; for i-thematic verbs tubi-ru, "to know, understand"; and for athematic verbs, k'e-ru, "to visit, go outwards".

	Imperfect	Perfect	Habitual
1sg ye	mis-a-yi	mis-e-y	mis-o-yi
2sg d'e	mis-a-d'ï	mis-e-d'	mis-o-n
3sg ko	mis-a	mis-e-k	mis-ou
1dl b'eya	mis-ä-vai	mis-e-vai	mis-ä-vai
2dl b'i	mis-ä-vai	mis-e-vai	mis-ä-vai
3dl b'an	mis-ä-nai	mis-e-nai	mis-ä-nai
1pl weja	mis-a-si	mis-e-s	mis-ä-ri
2pl soja	mis-a-ri	mis-e-r	mis-o-r
2pl zan	mis-a-r	mis-e-r	mis-o-r

Some generalizations that apply to