The possibility that parent-child relationships contain horizontal qualities that parallel comparable qualities in child-peer relationships is examined. It is argued that these qualities in parent-child relationships provide children with opportunities to experience and practice horizontal skills, which are then used in relationships with peers. To examine this prospect, horizontal qualities in parent-child relationships are first defined and illustrated. Particular reference is made to reciprocity and shared power in parent-child relationships, especially in contexts involving parent-child play and control exchanges. Developmental changes in the extent, nature, and role of horizontal qualities in parent-child relationships are discussed. Evidence is provided of wide individual differences among parent-child dyads in the degree to which horizontal qualities are exhibited. A case is developed for horizontality in parent-child relationships having consequences for children's development of peer skills and competence. Issues and limitations associated with claims about the presence and role of horizontal qualities in parent-child relationships are outlined, and directions for future research suggested.