Social presence is considered to be a major design principle in computer-mediated communication and an important determinant of online community participation. In this research, a multidimensional conceptualization of social presence that is more specific to online communities was developed and the potential of such a conceptualization to augment motivational theory was investigated to provide a better explanation of online community participation. More specifically, motivational theory and social presence theory are integrated to develop a model explaining online community participation. Different from prior research where social presence was assumed to be fully mediated through motivation, a direct effect of social presence on participation is hypothesized over and above those effects that are mediated by motivational variables. Three social presence dimensions of particular relevance toonline communities (i.e., awareness, affective social presence, and cognitive social presence) are identified and investigated. The results of an online survey provide strong support for the appropriateness of the multidimensional conceptualization of social presence and the research model. Theoretical and practical implications are discussed.