Little research has considered the nature of parent-child relationships in stable single-parent households that have not undergone transitions such as divorce and repartnering. This study explored how single mothers and their children negotiated their relationships in a context where the mother has been parenting alone continuously from early in the child's life. Thirty-eight children and adolescents and their mothers participated in qualitative semistructured interviews. Both mothers and children characterized their relationship as highly intense and exclusive. Perceived limitations in mothers' resources yielded opportunities for shifting dynamics of power and dependence where children adopted an ethic of care in their relationships with their mothers. In response to this, mothers worked to reaffirm clear distinctions between parent and child roles and protect against role boundaries becoming blurred by exercising their authority and managing children's exposure to household responsibilities. These findings provide insight into how mothers and children negotiated interdependence as they moved functionally between vertical and horizontal interactions in their relationship.