Belonging is a fundamental human need, deemed essential for optimal psychological functioning. There is, however, little consensus about how people gain feelings of belonging from social groups, with theories suggesting different antecedents depending upon how groups are conceptualised. The social identity perspective conceptualises groups as social categories and proposes that feelings of group belonging arise from perceived intragroup similarity. However, if groups are construed as interpersonal networks, feelings of belonging would be expected to arise from the quality of relationships and interactions among members. We tested these predictions using multilevel structural equation modelling of longitudinal data from 113 participants. We found that perceived intragroup similarity prospectively predicted feelings of belonging within groups perceived as social categories but not within those perceived as networks, whereas the quality of interpersonal bonds predicted feelings of belonging to both kinds of groups. We discuss the importance of distinguishing types of groups and suggest implications for research into group membership and well-being. Copyright © 2013 John Wiley & Sons, Ltd.