The distinction between new and old institutional economics may be unhelpful in depicting those theorists who defy clear categorisation. One such writer is Douglass North, who is associated with the new institutionalism but who deviates from the neoclassical principles which supposedly form the foundations of this school. The paper analyses his work to show how he combines both mainstream and alternative ideas. In attempting to reconcile individual agency with social structure, North suggests that institutions provide the constraints under which decisions are made but that individuals and organisations can alter those constraints. While his work is an attempt to advance interdisciplinary research, it fails to provide a fully integrated theoretical approach.