The study of social dominance has a long tradition within the peer relationships literature, but rarely has the topic been investigated observationally and longitudinally within other salient close relationships. The present study investigated the role of experiences in social relationships and adjustment indices in childhood in predicting later observed non-verbal social dominance behaviors in the context of romantic relationships in emerging adults. Analyses from a subsample (N = 70) from a 29-year prospective longitudinal study revealed links between early peer behavior and subsequent romantic relationship interactions for men and women. Non-verbal social dominance behaviors were concurrently associated with poor romantic relationship quality, conflict, and physical and verbal aggression within the dyad. Both childhood externalizing and internalizing behaviors significantly predicted non-verbal social dominance behaviors in the romantic partner interactions.