This is a study of the interrelationships between religious traditions and domestic vernacular architecture. Through a comparative study of two religious groups — the Zoroastrians and the Muslims — in Iran, we describe the influence of their religious traditions, beliefs, values, rituals, and religion-legitimated social conduct on the houses of each religious group. Utilizing an antipositivist perspective, we also describe the influence on their houses of the interaction of these two groups and their cultures, as well as the effects of differential power and hegemonic relations. We draw several theoretical lessons from this comparative cultural study and examine issues related to the adequacy of positivist, modernist studies, and the potential of an antipositivist perspective in environmental design research.