Mentalization is a psychological concept that describes the ability to understand the mental state of oneself and others which underlies overt behaviour. Mentalization can be seen as a form of imaginative mental activity, which allows us to perceive and interpret human behaviour in terms of intentional mental states (e.g. needs, desires, feelings, beliefs, goals, purposes, and reasons). 
While the Theory of Mind has been discussed in philosophy at least since Descartes, the concept of mentalization emerged in psychoanalytic literature in the late 1960s, and became empirically tested in 1983 when Heinz Wimmer and Josef Perner ran the first experiment to investigate when children can understand false belief, inspired by Daniel Dennett's interpretation of a Punch and Judy scene. The field diversified in the early 1990s when Simon Baron-Cohen and Uta Frith, building on the Wimmer and Perner study, and others merged it with research on the psychological and biological mechanisms underlying autism and schizophrenia. Concomitantly, Peter Fonagy and colleagues applied it to developmental psychopathology in the context of attachment relationships gone awry. More recently, several child mental health researchers such as Arietta Slade, John Grienenberger, Alicia Lieberman, Daniel Schechter, and Susan Coates have applied mentalization both to research on parenting and to clinical interventions with parents, infants, and young children.
Mentalization has implications for attachment theory as well as self-development. According to Peter Fonagy, individuals without proper attachment (e.g. due to physical, psychological or sexual abuse), can have greater difficulties in the development of mentalization-abilities. Attachment history partially determines the strength of mentalizing capacity of individuals. Securely-attached individuals tend to have had a primary caregiver that has more complex and sophisticated mentalizing abilities. As a consequence, these children possess more robust capacities to represent the states of their own and other people’s minds. Early childhood exposure to mentalization can serve to protect the individual from psychosocial adversity.  This theory needs further empirical support.
- UCL (Psychoanalysis Unit) Peter Fonagy's Homepage
- Psychotherapy for Borderline Personality Disorder. Workshop on Mentalisation Based Treatment. Anthony Bateman & Peter Fonagy
- Fonagy, P., Gergely, G., Jurist, E.L., Target, M. (2002). Affect regulation, mentalization and the development of the self. New York; Other Press
- Wimmer, H.; Perner, J. (1983). "Beliefs about beliefs: Representation and constraining function of wrong beliefs in young children's understanding of deception". Cognition 13 (1): 103–128. doi:10.1016/0010-0277(83)90004-5. PMID 6681741.
- Allen, J. P., Fonagy, P. (Eds.), Handbook of Mentalization-Based Treatment. Chichester, UK: John Wiley & Sons
- Slade, A. (2005). Parental reflective functioning: An introduction. Attachment and Human Development, 7(3), 269-283.
- Grienenberger JF, Kelly K, Slade A (2005). Maternal reflective functioning, mother-infant affective communication, and infant attachment: Exploring the link between mental states and observed caregiving behavior in the intergenerational transmission of attachment. Attachment & Human Development, 7(3), 299-311.
- Lieberman, A.F., Van Horn, P., Ippen, C.G. (2005). Towards evidence-based treatment: Child-parent psychotherapy with preschoolers exposed to marital violence. Journal of the American Academy of Child and Adolescent Psychiatry, 44, 1241-1248.
- Schechter DS, Myers MM, Brunelli SA, Coates SW, Zeanah CH, Davies M, Grienenberger JF, Marshall RD, McCaw JE, Trabka KA, Liebowitz MR (2006). Traumatized mothers can change their minds about their toddlers: Understanding how a novel use of videofeedback supports positive change of maternal attributions. Infant Mental Health Journal, 27(5), 429-448.
- Coates, S.W. (1998). Having a Mind of One's Own and Holding the Other In Mind. Psychoanalytic Dialogues, 8, 115-148.
- Mechanisms of change in mentalization-based treatment of BPD. J Clin Psychol. 2006 Apr;62(4):411-30. Fonagy P, Bateman AW.
- Apperly, I. (2010). Mindreaders: The Cognitive Basis of "Theory of Mind". Hove, UK: Psychology Press.
- Doherty, M.J. (2009). Theory of Mind: How Children Understand Others' Thoughts and Feelings. Hove, UK: Psychology Press.
- Anthony Bateman's homepage.
- Mentalization factoids – compiled by Frederick Leonhardt. A summary of mentalization.
- Ara Norenzayan, Will M. Gervais, Kali H. Trzesniewski. Mentalizing Deficits Constrain Belief in a Personal God // PLoS ONE 7(5): e36880. May 30, 2012. Doi:10.1371/journal.pone.0036880.