Campbell's (1958) concept of ingroup entitativity is reformulated as a perceived interconnection of self and others. A 2 (intergroup relations: competitive, neutral)×3 (intragroup interaction: low, medium, high) between-subjects design was used to examine (1) the effects of intergroup and intragroup relations on perceived ingroup entitativity and (2) the relation between ingroup entitativity and intergroup bias. Regardless of the relations between groups, members who experienced intragroup interaction had stronger perceptions of ingroup entitativity and stronger representations of the aggregate of ingroup and outgroup members as two separate groups than members who lacked intragroup interaction. Furthermore, perceptions of ingroup entitativity mediated the effect of the salience of the intergroup boundary on behavioral intergroup bias. These results call into question the ‘intergroup’ nature of group based phenomena. An ingroup entitativity framework is presented that locates the source of group-based phenomena (e.g. intergroup bias) in intragroup processes. Copyright © 1998 John Wiley & Sons, Ltd.