Objective This study examines the association between parental relationship churning (i.e., the separation and reunification of one's biological parents) and adolescent well-being. Background Research examines how instability in parental romantic relationships is linked to adolescent well-being, but it has largely neglected instability and transitions that occur within, rather than between, relationships. Family stress and family boundary ambiguity theories suggest that adolescents from churning families will experience deleterious outcomes when compared with their counterparts in stably together families. Method In this article, the authors used data from the Fragile Families and Child Wellbeing Study (N = 3,327) to examine the association between parental relationship churning and adolescent socioemotional and behavioral outcomes (including internalizing behaviors, externalizing behaviors, depressive symptoms, anxiety, delinquency, and exclusionary school discipline experience). Results Adolescents who experience parental relationship churning between birth and age 9 had similar outcomes to their counterparts with stably together parents or parents who dissolve their union and repartner, net of demographic and socioeconomic characteristics. Adolescents who experience parental relationship churning, compared with those who experience parental union dissolution without repartnership, had more externalizing problems. The associations were similar for boys and girls. Conclusions Differences in adolescents' outcomes by parental relationship history were largely driven by the variation in parental characteristics. These selection factors, however, did not similarly explain all of the differences between adolescents with churning parents and adolescents who experienced union dissolution without repartnering. This underlines the potential importance of distinguishing between different types of family instability experiences.