What do we envision when we hear “American family?” How is the definition of ‘family’ changing and why? Whether nuclear, step, foster, extended, transnational, adoptive, or informal, American families are more diverse than ever. The structures of families are changing. Families, now more than ever, are influenced by other social and cultural shifts, such as the rise of single parent households, divorce, opting for cohabitation over marriage, and same-sex marriage. Each of these new definitions of family is rooted in broader economic and social changes that are underway in the U.S. and around the world.