Attendant to the exponential increase in rates of incarceration of mothers with young children in the United States, programming has been established to help mothers attend to parenting skills and other family concerns while incarcerated. Unfortunately, most programs overlook the important, ongoing relationship between incarcerated mothers and family members caring for their children—most often, the inmates' own mothers. Research reveals that children's behavior problems escalate when different co-caregivers fail to coordinate parenting efforts and interventions, work in opposition, or disparage or undermine one another. This article presents relevant research on co-caregiving and child adjustment, highlights major knowledge gaps in need of study to better understand incarcerated mothers and their families, and proposes that existing interventions with such mothers can be strengthened through targeting and cultivating functional coparenting alliances in families.