Within the discipline of community psychology there is debate as to the dimensions underlying the construct psychological sense of community (PSOC). One of the few theoretical discussions is that of McMillan and Chavis (1986), who hypothesized four dimensions: Belonging; Fulfillment of Needs; Influence; and Shared Connections. Discussion has also emerged in the literature regarding the role of identification within PSOC. It has been suggested that differences in PSOC may be understood in terms of the degree to which members identify with their community (Fisher & Sonn, 1999). However, few studies have explored the place of identification in PSOC. In addition, while PSOC has been applied to both communities of interest and geographical communities, little research has looked in depth at PSOC within communities of interest. The current study therefore explored PSOC in science fiction fandom, a community of interest with membership from all over the world, by means of a questionnaire distributed at an international science fiction convention (N = 359). In an endeavor to clarify the underlying dimensions of PSOC, the questionnaire included several measures of PSOC, and measures of identification with the community. Results showed that science fiction fandom reported high levels of PSOC. Support emerged for McMillan and Chavis' (1986) four dimensions of PSOC, with the addition of a fifth dimension, that of Conscious Identification. These results, and implications for PSOC research, are discussed.