This volume is an important contribution to the diachrony of non-canonical subjects in a typological perspective. The questions addressed concern the internal mechanisms and triggers for various changes that non-canonical subjects undergo, ranging from semantic motivations to purely structural explanations. The discussion encompasses the whole life-cycle of non-canonical subjects: from their emergence out of non-subject arguments to their expansion, demise or canonicization, focusing primarily on syntactic changes and changes in case-marking. The volume offers a number of different case studies comprising such languages as Italian, Spanish, Old Norse and Russian as well as languages less studied in this context, such as Latin, Classical Armenian, Baltic languages and some East Caucasian languages. Typological generalizations in the form of recurrent developmental paths are offered on the basis of data presented in this volume and in the literature.