The term reflective function (RF) refers to the psychological processes underlying the capacity to mentalize, a concept which has been described in both the psychoanalytic (Fonagy, 1989; 1991) and cognitive psychology literatures (e.g. Morton & Frith, 1995). Reflective functioning or mentalization is the active expression of this psychological capacity intimately related to the representation of the self (Fonagy & Target, 1995; 996; Target & Fonagy, 1996). RF involves both a self-reflective and an interpersonal component that ideally provides the individual with a well-developed capacity to distinguish inner from outer reality, pretend from ‘real’ modes of functioning, intra-personal mental and emotional processes from interpersonal communications. Because of the inherently interpersonal origins to how the reflective capacity develops and expresses itself, this manual refers to reflective functioning, and no longer of reflective-self functioning (see Fonagy, Steele, Moran, Steele, & Higgitt, 1991a), as the latter term is too easily reduced to self-reflection which is only part of what is intended by the concept.