Transience, or residential mobility, is the reality for many working-class and impoverished urban people. This was as much the case in the nineteenth century as it is today. Based on examinations of nineteenth- and twentieth-century demographic patterns and individual or household movements in a variety of Toronto neighbourhoods, it is possible that such movement was even greater in the past. Likewise, household composition could be far from stable, depending on changing fortunes and circumstances, and they were not always defined by family ties. What are the effects of these factors on our understandings of nineteenth-century urban domestic sites? Are prevailing assumptions of the primacy of the stable household as the fundamental analytical and interpretive unit legitimate in poorer working-class urban settings? Review of the occupational histories and archaeological records of three residential sites in the St. Andrew’s Ward of Toronto provides a point of departure to begin to explore these types of questions, which are ultimately all related to the fact that cities, and their inhabitants, are in constant states of change.