A brief study of twins and their relationship quickly reveals what is known as the ‘twin bond’. This article explores the ways in which the twin bond differs from all other attachment bonds formed in the lifetime of a human being. The article shows how different the bonding is between identical and fraternal twins with a view to examining the psychology of ‘wombtwin survivors’, people who started life as a twin but whose co-twin died before birth. The study reveals how the twin attachment bond is created in the womb at the very beginning of life and lasts a lifetime. Wombtwin survivors display many of the same characteristics of twins who are born together, for the effects of the bond between twins - the preoccupation; the paradox; the lack of a sense of identity and the need for the physical presence of the lost co-twin - is also present in the life of the sole survivor.