By sponsoring, promoting or simply monitoring virtual communities related to their products, work processes, and other topics of interest, organizations leverage the efforts, insights, and abilities of individuals inside and outside their organization. Lurkers are participants who persistently demure from engaging in the core activities that sustain a virtual community. Because virtual communities are perpetuated through voluntary contributions, the persistent peripheral participation of lurkers is sometimes viewed negatively as social loafing or free-riding. Alternatively, an individual may engage in legitimate peripheral participation when their passive monitoring of group activities educates, socializes, and otherwise prepares them for more effective contribution. We reconcile these conflicting views of lurking with individual- and community-level models of peripheral participation that include a parsimonious typology of virtual communities. Through empirical tests based on over 395,000 observations gathered over five months from 548 online discussion forums, we demonstrate how lurking effects growth in site membership and participation. We conclude that lurking as legitimate or illegitimate peripheral participation is context-dependent and a more complex, nuanced activity than previously theorized and measured.