The thesis proposes a projective theory for contemporary urbanism that equates the active processes of the city and a new orientation for procedural urban design within a single line of thought that delineates the concept of a generic organization—one that derives from unitary operations acting in series, forming heterogeneous assemblages, but resisting the tendency to totalizing systematization. Such a description characterizes the urban condition as an open phenomenon, such as that described by theorists of assemblage urbanism. This thesis extends this work from an analytical or empirical theory to an operative one that can be applied to design practice by combining it with an ontology of encapsulation and object-based agency. I will argue that computational processes are unique in the way that they enable urban design to operate in the same manner as the city with regard to enaction and representation while drawing attention to the rhetorical dimension of interactive systems like urbanism and procedural models. These parallels are further explored through a series of themes that bridge between urban studies and urban design and that connect to historical concerns in computation and urban design. The four themes—Interactive, Generative, Reflexive, Entropic—coalesce around a coherent, integrated theoretical schema. Within this framework, I also argue for an increasingly involved role for architecture as an active agent in the urban design process. Illustrations of how this might occur (as functional code and software screenshots) are presented alongside the arguments to underscore the fact that the material basis of the computational model is as significant a determinant of design practice as the material realities of the city are to the urban experience. Finally, these lessons are imported back into urbanism with architecture serving as an interface to the city. Procedural engagement allows architecture to participate in urbanism through an inextricably and mutually contingent interaction. In cases where this occurs, the city continuously prompts architecture to carry out new inquiries into the changing potential of the urban situation, without providing a terminal condition. Rather, by allowing the the outcome of the situation to remain undecided, both urbanism and computational modeling can be seen to offer the same productive irreality and alterity: an urban generic.