Research on online communities has emphasized the individual benefits of social support for members, but less is known about how such communities are regulated through organizing processes of support and control. Drawing on a survey of 214 members of a particular online message board community, we develop and test a model of social support, strength of ties, normative influence, and concertive control and their influence on members’ sense of virtual community (SOVC). We find that all four factors predict SOVC, but that normative influence and concertive control have the strongest effects. Furthermore, social support and concertive control mediate the effects of number of strong ties and normative influence (respectively) on SOVC. Finally, we find no association between SOVC and time-lagged posting frequency. Our findings have important implications for understanding the factors that lead to attachment in online communities, and they suggest that sense of belonging works through tandem communicative processes of support and control.