Qualitative instrumental case study analysis of adult siblings from 2 families explores how socioeconomic inequality among them affects their relationships to one another. Eight middle-aged siblings' observations of childhood, parental expectations, work and family history, lifestyle, and current sibling ties indicate that childhood interdependence, parallel parental treatment, similar intergenerational mobility, greater success of the younger rather than older siblings, and economic success due to other than individual effort facilitate smoother negotiations of material inequality and enhance the negotiation of sibling relationships as important sources of support. These new insights on negotiating sibling ties over time are related to various forms of capital, a life course perspective, and ambivalence, and point to fresh avenues for future research and theory.