This article is an analysis of the frequency and characteristics of unrelated individuals between 1900 and 1950. The much-heralded rise of the primary individual during the 20th century has been offset by a decline in the frequency of secondary individuals. The overall percentage of persons residing without family did not exceed turn-of-the-century levels until the 1970s. Using data from national micro data samples of the census for 1900, 1940, and 1950, the study applies decomposition techniques and life-course analysis to investigate these patterns. The results show that the decline of the secondary individual from 1900 to 1950 was largely a function of changing demographic composition, but the increase of primary individuals is linked to changing residential preferences.