A social identity approach to the investigation of group-based reactions to a merger is outlined, in which a merger is analyzed in terms of the continuation or change of the pre-merger group identity. In two experiments, the relationship between pre-merger identification, post-merger identification, and ingroup bias was investigated using a minimal group paradigm. Results from both studies showed that the perceived continuation of the pre-merger group identity in the post-merger group strengthened the positive relationship between pre-merger identification and identification with the superordinate post-merger group. Moreover, perceived continuation strengthened, rather than reduced, ingroup bias at the subordinate level of the merged groups. Some theoretical and practical implications are discussed.