This dissertation addresses the question of how architectural knowledge—information about design and construction that was necessary to produce a building—was transmitted in the Roman world. It examines theater buildings in the northwestern provinces of the Roman Empire between the first century BCE and fourth century CE, an extensive and varied corpus that attests to the progressive adoption and adaptation of a new building type in a provincial context where it had not previously existed. The northwestern theaters were atypical compared to those elsewhere in the Empire, and the dissertation turns to the field of network analysis for tools to evaluate how the differential spread of architectural knowledge through an ancient social network produced the formal divergences evident in the Northwest. The analysis consists of a broad computational synthesis of patterns in theater architecture founded on a close study of archaeological evidence from the buildings. I evaluate architectural elements that reflect informed choices made by architects and builders, including the plans and elevations of canonical western Mediterranean type theaters in southeastern Gaul and the stages and seating areas of non-canonical theaters throughout the study area. I consider the impact of factors such as formal models, connective infrastructure, construction materials, performance practices, and indigenous construction traditions on regional knowledge transmission and innovation. After addressing each feature and factor in turn, I bring them together in a quantitative social network analysis, examining patterns in the data using statistical testing. The dissertation concludes that theater architecture in the Northwest reflected the structures of societal networks that rearranged as Rome intervened in the region. It identifies incongruent patterns in the distribution of individual architectural features among the theater buildings, suggesting that architects combined elements from many sources to create designs that incrementally diverged from their models. The results of this project highlight how patterns of social interaction and transaction across time and space generated variation in the theater corpus, and reveal the central position of knowledge transmission networks in the globalization of Roman architecture.