Peter Fonagy and Mary Target have added to the attachment literature with their dual concepts of self-reflective functioning and mentalization. They propose that security of attachment in adulthood involves the capacity for self-reflective functioning, which means the ability to reflect upon one’s emotional experiences in a thoughtful and coherent way. The ability to mentalize emotional experiences involves the capacity to represent one’s own and others’ mental experiences; that is, to understand and grasp the nature of emotional experience. In their view, the child’s security of attachment is not only dependent on the mother’s sensitive behavior but also on her psychological sensitivity. When the mother can keep her child’s subjective experience in mind, she teaches the child that emotions both can be understood and communicated. The child’s development of self-reflective functioning is therefore dependent upon the mother’s mentalization of the child’s experiences. Fonagy and Target have applied these concepts to their work with adults with severe personality disorders, many of whom sorely lack both self-reflective and mentalization abilities.