The number of incarcerated mothers has risen steadily in the past 20 years, with a majority of the mothers’ children being cared for by relatives, usually the maternal grandmother (Smith, Krisman, Strozier, & Marley, 2004). This article examines the unique coparenting relationship of grandmothers and mothers through qualitative individual interviews with a sample of 24 incarcerated mothers with children between the ages of 2 and 6, and 24 grandmothers raising their children. The study revealed many different variants of healthy coparenting alliances, achieved against often huge odds. Much variation was also discovered in dyads where coparenting alliances were not as successful. Implications for practice include performing structural family assessments, enhancing jail education programs, and offering extended coparenting treatment after discharge.