Poverty, a social determinant of health, disproportionately affects families with children. Public and private safety nets, or support networks available in times of need, can help address poverty and its consequences. Independently, strong safety nets (public or private) promote health and well-being, yet little is known about how private and public safety nets combine and evolve over time. Using latent class and latent transition analyses, this study examined public and private safety net configurations of mothers with low-income, sociodemographic characteristics associated with these configurations, and safety net changes over time. Using data from the Future of Families and Child Wellbeing Study from child ages 1, 5, and 9 (N = 2,251), results indicated that mothers were sorted into four safety net configurations (public support only, private support only, all high, and all low) and 30%-53% of each class of mothers transitioned from one safety net configuration to another at the next neighboring wave, underscoring the importance of examining both public and private supports simultaneously and longitudinally. Membership in configurations with low private support (e.g., public only, all low) and sociodemographic disadvantage (e.g., more poverty, recent experience of hardship) predicted transitions, commonly leaving mothers without advantage in the riskiest safety nets. To promote a more responsive, equitable safety net, lengthening public safety net program certification periods and increasing outreach efforts (e.g., through schools, churches) to potentially eligible mothers could strengthen and stabilize safety nets to lessen poverty and its consequences for economically marginalized families. (PsycInfo Database Record (c) 2024 APA, all rights reserved).