The frequencies of collective behavior are getting higher in virtual communities. Most studies regard-ing collective behavior on Internet focuses on investigating the behavior per se, and few are addressing the contributing factors and the moderating effects of the community platforms. Even if a swarm of people gathering and interacting on virtual communities, they are just one single person sitting behind their individual computers and using their created identities to act. Spatially, they are not assembled at the same spot; therefore the effect of emotional contagion is restricted. Temporarily, they are not con-centrated at the same time; as a result they have more time to react. This study thus proposed the con-cept of Quasi-collective Behavior to denote collective behavior on virtual communities and make dis-tinctions with general collective behavior in physical world. Since people are not gathered at the same physical place, the ambiance of the virtual space is obviously transmitted by the community platforms. This study employs the notion of para-social presence to be the moderator influencing contributors on quasi-collective behavior. We plan to examine the proposed model and expect to gain insights into the quasi-collective behavior and thereby provide practical managerial implications.