Rapidly rising rates of premarital cohabitation and nonfamily living have coincided with dramatic changes in family formation attitudes in the United States. This article examines the impact of nonfamily living arrangements and cohabitation on changes in family formation attitudes at the individual level. The theoretical framework focuses on the role of learning processes and cognitive consistency. This framework also draws similarities and differences between the likely impact of cohabitation and that of other living arrangements. Empirical analyses demonstrate that both the experience and duration of cohabiting arrangements have significant effects on family formation attitudes but fail to show significant consequences of premarital, nonfamily living arrangements. The findings provide insights into the consequences of new living arrangements for changes in family formation attitudes in early adulthood.