This paper presents an attempt to establish qualitative and quantitative methods for measuring the transitivity of Latin textual genres. Traditionally defined as the capacity of a verb to pass the action from the subject to the object, transitivity is recognised as a descriptive feature of genres by modern-language studies. This study is based on a syntactically annotated corpus of Early Medieval documentary Latin (LLCT). Transitivity is first approached in terms of a classificatory analysis of the most common verbs of the corpus, which is then followed by a functionally-inspired transitivity component analysis of a sample (N = 810). The Latin documentary genre appears to have a bipolar transitivity profile symptomatic of its dual communicative function: the performative verbs typical of the dispositive legal language are high in transitivity, whereas the frequent relational verbs which connect concepts and properties are low. The method is expected to be extendible to other Latin genres, such as narrative and oratory.