This paper presents an interview study of how social network communication media, Facebook specifically, can facilitate and influence proximal communities. We investigated scenarios in which users integrated their online interactions with offline activities. We found that Facebook heightened the visibility of social identities, but that these identities are multifaceted and dynamically modulated by context. We found that Facebook broadly facilitated offline activities from proposing and planning through to report and commenting. We found that people use Facebook features differentially as they maintain strong and weak ties. Finally we discussed how social identities, social engagements, and social ties are mutually reinforcing and cultivating with the affordances of Facebook.