The architecture of the modern Hopi pueblo of Oraibi provides important data for the interpretation of prehistoric villages in the American Southwest and elsewhere. Using historic photographs, maps, and other documents, architectural change at Oraibi is examined over a period of almost 80 years, from the early 1870s to 1948, a span that includes an episode of population growth and a substantial and rapid population decline. Because archaeologists make extensive use architecture for a variety of types of prehistoric reconstructions, from population size to social organization, understanding the dynamics of puebloan architecture is important. This study offers several principals which condition architectural dynamics in pueblo-like structures in the Southwest and in other parts of the world. Four types of architectural change are identified at Oraibi: rooms were abandoned, dismantled, rebuilt, and newly constructed. Some changes were the result of the introduction of EuroAmerican technology and governmental policies. An increase in the rate of architectural change, especially new construction and rebuilding, suggests that population was increasing during the late 19th century. Patterns of settlement growth involved both the expansion of existing houses and the construction of new houses. Oraibi architecture, with contiguous rows of houses, may have restricted the development of extended families. After the 1906 Oraibi split, half the population left the village, and in the following decades, population continued to decline. Abandoned houses were often rebuilt and reoccupied by remaining residents. The number of rooms per house declined, especially upper story rooms. The areas of the settlement that continued to be occupied or were reoccupied were those around important ceremonial areas, such as the Main Plaza. The examination of architecture at historic Oraibi supplies links between social processes and architectural dynamics that are applicable to the prehistoric record. Patterns of intra-household architectural change and of settlement growth and abandonment, observed at Oraibi, provide keys to the investigation of similar processes at prehistoric sites.