A special issue of The Journal of Architecture guest edited by Sam Jacoby. During the nineteenth century, a deliberate turn away from ideas of imitation and truth-to-nature towards concepts of abstraction or objectivity emerged and fundamentally altered the knowledge and practices of many disciplines. In architecture, this important shift resulted in theories of type and design methods based on typology, complementary concepts through which architecture as both a modern form of knowledge and knowledge of form was to be consolidated. In terms of architecture and its instrumentality, type and typology are unique as disciplinary frames through which broader socio-political, cultural and formal problems can be posed. To explore the sustained, or perhaps renewed critical, interest in the potential of type and typology, a number of academics and practitioners discuss their relevance to contemporary architectural practice and research and in relationship to the problem of the historicity of disciplinary knowledge.