This book deals with systems of verb classification in Australian Aboriginal languages, with particular focus on languages of the north-west. It proposes a typology of the systems according to their main formal and semantic characteristics. It also makes some proposals concerning the historical origins and grammaticisation of these systems, and suggestions regarding the grammatical relations involved. In addition, an attempt is made to situate the phenomenon of verb classification within the context of related verbal phenomena such as serial verb constructions, nominal incorporation, and complex predicates.