The opportunities provided by large social networks are obvious. There are more people to socialize with and to provide social capital. There is the possibility for more diversity in larger networks, and that expands the kinds of experiences people share within a network and the kinds of resources they contribute.

Yet large networks can also be a burden. It takes time and energy to maintain a large network, especially when it comprises not a single solidary group but a fragmented group with many discrete clusters and relationships. More ties can also mean more requests for social capital. Increased opportunity for socializing may bring the burden of too-frequent conviviality.

How does people’s email use correlate with the size of their social networks? On the one hand, email allows for flexible interaction because it is asynchronous — messages sit there until they are read — and provides the user more control over the length of time invested in each interaction than either in-person or phone contact. But the accessibility of email may also be burdensome. People are more willing to contact each other by email than by knocking on doors or making telephone calls. It scarcely costs them any more time to send an email message to many people than to just one. Hence, email can support the growth of communication, especially as it adds on to — rather than replaces — in-person and even phone contact.