In light of waning interpersonal contact in America, scholars have turned their attention to social network sites and the opportunities these provide for building and maintaining social relationships. The present study adds to this research, using national survey data from U.S. adults to examine how motivated use of Facebook for expanding and diversifying personal networks might revitalize real-world efforts of sociability for users, and returns to social capital that come by way of them. Results support our overall model relating weak-tie interactions to generalized trust. More importantly, when we use it to compare more and less sociable Facebook users, we find meaningful differences in the strength of the relationships between variables in the model. In particular, for more sociable users, interacting with weak ties was related to greater civic participation and increased feelings of generalized trust. Access to bridging social capital was a larger source of generalized trust for more sociable users as well. Ultimately, our findings suggest that sociability on sites like Facebook can facilitate the development of communication competence, where users who make a concerted effort of expanding and diversifying their personal networks come to interact with a wider array of individuals, and learn how to do so more effectively.