We have presented the intensive treatment of a young woman whose chronic suicidality had resulted from a delusional merger with a brother who had died during her childhood. The case

offered a particularly clear example of derailment of the developmental process of self-differentiation, leading to the formation of a highly pathological introject and delusion of merger. Emphasis was placed on the repetitive and selfobject aspects of the transference bond that became established and on how the analysis of these shifting dimensions of the transference contributed to the therapeutic process.