This dissertation intends to switch the focus from the study of traditional parental relationships to look at other family and household structures. It examines the dynamics of formation and dissolution of extended-family households in the U.S., and the economic consequences of marriage and cohabitation dissolution for women in Colombia. It includes three empirical chapters conducting secondary data analysis of two large-scale surveys. The first two studies use the Fragile Families and Child Wellbeing Study and its restricted contextual data to document the prevalence, duration and correlates of formation and dissolution of three-generation households in the U.S., paying particular attention to differences by race and ethnicity. Results indicate that three-generation households are more common among racial and ethnic minorities, usually short-lived, common early in a child’s life, and that the probability of entry decreases as children age. In addition, they indicate that while children are exposed to parental changes, they are also exposed to non-parental transitions. Moreover, both economic and non-economic factors are associated with the formation and dissolution of three-generation households. As three-generation households in the U.S. continue to rise, these findings highlight the need to examine the role of family and household changes concurrently to better understand their role on children wellbeing, and they suggest the need to examine the use of the private and public safety net. The third study uses the Colombian Longitudinal Survey (ELCA) to examine the consequences of marriage and cohabitation dissolution on women’s economic well-being, in comparison to six OECD countries. Results suggest that women who experience the dissolution of their unions in Colombia are usually more socioeconomically advantaged than those who do not, and that they do not experience a significant decrease on their economic well-being post-dissolution. Findings indicate that private transfers from family and friends play an important role in mitigating the effect of union dissolution on women’s economic well-being. Overall, this dissertation highlights the role that the private safety net plays in supporting women and children, both in cash support from family and friends and in co-residence, and it calls for the study of alternative living arrangements to the nuclear family.