Twinship has a fateful effect not only on the twins themselves but on all the other members of the family, especially the siblings. The cases presented in this paper demonstrate that the nontwin sibling reacts to the arrival of twins with intensified sibling rivalry and a pervasive sense of being excluded from the rest of the family of couples—mother and father, the twins. In the attempt to compensate for these feelings of incompleteness and loneliness the siblings of twins unconsciously but unsuccessfully and interminably seek a twin surrogate. Thus, the reality of being a sibling of twins is very different from the fantasy of having a twin.