The Sense of Community Index (SCI) is one of the most commonly used measures of Psychological Sense of Community (PSOC). There is much discussion in the literature as to the validity of the scale as a measure not only of overall PSOC, but also of the dimensions (Membership, Influence, Needs Fulfillment, and Emotional Connection) theorized by McMillan and Chavis (1986) to underlie the construct. The current paper examines the factor structure of SCI in a study ( N = 219) that examines multiple community memberships, including neighborhood, student, and interest group communities. Data was analyzed by confirmatory factor analysis (CFA). The results showed that the SCI, in its original factor structure, did not adequately fit the data. The scale was revised, therefore, using CFA indicators, to produce a new four-factor structure based on the same items. This revised model was tested and found to display adequate fit indices to the data in all three communities. The results of the study provide empirical support for retaining measures that encapsulate the four dimensions of PSOC. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 691–705, 2004.