This paper reports a statistical analysis of people's movements among household types. At any point in time, persons in one household type are at risk of joining some other type. Correspondingly, the structure of an existing household may change when someone else joins it, depending on the new person's relation to the members already present. The authors model this dynamic process using data from 13 successive waves of the Panel Study of Income Dynamics that span 1968 through 1980. They subject individuals' spells (durations in a type) to a hazards analysis with competing risks, including as covariates age, race, sex, family income, and the year the spell began. Using this methodology, they develop a map of the flow of individuals among household types, along with demographic and economic profiles of individuals making the transitions. The results reveal wide variation in the stability of household types, with nuclear families the most stable. Marked racial differences appear in both the relative stability of certain types and in the pattern of destination choices.