Nearly half of all poor, urban renters in the United States live in rental buildings of fewer than four units, and such buildings make up nearly half our nation's rental housing stock. Yet small rental properties remain largely overlooked by researchers. We present two reportsfrom New York City and Baltimoreboth providing suggestive evidence, drawn from a variety of sources, about the characteristics of small rental housing. We find that while small buildings offer lower rents and play a crucial role in housing low-income renters, these lower rents are largely explained by neighborhood location, however, ownership matters.