Museums are organizations that need to maintain relationships with several stakeholders in order to achieve their economic and social objectives. In this context, the current paper explores the effect of an organization’s bonding social capital and a manager’s social capital on the organization’s ability to build external relationships, in other words, bridging social capital. Results from the study indicate that the structure of internal social capital (cohesion and diversity) and the manager’s role as a bridging tie facilitate relations with stakeholders and other museum networks. Moreover, collective social capital (bonding and bridging) has a direct impact on innovative proposals, on the museum’s image and on incomes, all of which entail key management implications.