This article integrates relationship marketing and social network perspectives to develop and test a model that links objective sales performance with the informational and cooperative benefits that stem from relationship managers' (RMs') social capital structure (brokerage and density) and relations (formal and informal networks). The authors demonstrate the effect of cross-network and overlap-network synergies on performance. Data about both formal and informal networks of 464 employees, including 101 RMs, demonstrate that RMs' performance improves with cross-network synergy when informational benefits from wide-reaching, nonoverlapping ties in the informal network combine with the cooperative benefits of a densely interconnected formal network. In addition, the effects of formal and informal social capital structure on performance increase significantly when RMs have a high degree of network overlap between their formal and informal networks.