Scholars have called for better understanding of the generative process, a process underlying the creation of urban form that often has positive qualities such as coherence, human scale, flexibility, and adaptability. The generative process is incremental and continually refined, producing urban settlements that respond to feedback. Redefining the pattern language as a system of knowledge generation, and a method to acquire essential information and re-create historical contexts, this dissertation aims to provide a comprehensive understanding of the generative process and the corresponding urban codes of traditional cities. The dissertation consists of three complete yet interconnecting articles. The first article examines the structural components of the generative process— place-based norms and urban codes—and their roles in generative development. Two traditions of urbanism with distinctive and coherent forms and different levels of imposed regulations were investigated: medieval European and Arabic-Islamic. The study finds that place-based norms are the core of any generative process. Whenever written codes do not control urban space, these norms emerge to operationalize the building process. The second article investigates the generative process through the operationality of patterns, properties, and a sequence in the creation of the traditional form of the town of Hoian, Vietnam. The recurrence of each property and the pattern of its repetition in urban elements are investigated to assess the impact of generative forces on the urban form of Hoian. Fifteen of Alexander’s properties and ten of Lynch’s qualities were also combined into a set of twenty properties of urban elements. Finally, the third article observes and then explores the unfolding of the generative process using the virtual online platform OpenSim, thereby verifying the operationality of the generative process revealed in the previous two articles. The paper substantiates the proposition that the generative system includes patterns and urban properties that can serve as rules for directing urban growth. These rules build diverse and unified urban settlements.