Split intransitivity has been an important issue in syntactic theory since the postulation of the Unaccusative Hypothesis in Relational Grammar in Perlmutter 1978; it was adapted into Government-Binding theory in Burzio 1981. In both theories, a purely syntactic approach to split intransitivity is taken. This paper argues that split-intransitive phenomena are better explained in semantic terms. The semantic analysis will be carried out in Role and Reference Grammar, which assumes the theory of verb classification proposed in Dowty 1979. The analysis will focus on Italian, Georgian, and Acehnese, languages which have been cited as providing support for the UH. It will be shown that two semantic parameters, inherent lexical aspect (Aktionsart) and agentivity, underlie split intransitivity crosslinguistically.