I am concerned with a very problematic concept of identity which one encounters in studies of practical problems concerning the adoption of children. The notion is problematic in the extreme, as I shall try to show. It seems to crop up not only in the work of researchers on this topic, but in the spontaneous and (apparently) untutored accounts of themselves given by adoptees. The question is whether there is a concept here at all: by which I mean not, instead, a family of concepts linked by family resemblances, but rather some disparate ideas linked only by verbal similarities, and run together for mistaken theoretical purposes. The notion arises crucially in attempts to deal with practical questions arising in determining policies with regard to adoption: with regard to the placement of children for adoption, and the advice to be given to adoptive parents and to adopted children, whether young or adult, who encounter, or perhaps do not even encounter, difficulties.