Effective workgroups engage in team boundary spanning, that is, using communication ties as conduits to critical external resources. The proliferation of enterprise social media (ESM) and the associated increase in visibility of people, content, and interactions, has resulted in a widespread assumption that unlimited visibility improves boundary spanning. Consequently, the ESM literature has generally ignored the sentry functions of teams and failed to examine the possible strategic nature of visibility choices by ESM groups. Using log and content data from 655 ESM-based workgroups at a multinational enterprise, we contribute a deeper understanding of the distinct ways that ESM visibility-bounded or unbounded-is leveraged strategically to evoke diverse network structures, which in turn have implications for distinct boundary-spanning activities. Practically, these findings show that ESM present a unique opportunity for workgroups to simultaneously sustain multiple virtual spaces-with varying levels of visibility-through which they can manage their diverse boundary-spanning goals.