Mentalization-based treatment (MBT) is an integrative form of psychotherapy, bringing together aspects of psychodynamic, cognitive-behavioral, systemic and ecological approaches. MBT was developed and manualised by Peter Fonagy and Anthony Bateman, designed for individuals with borderline personality disorder (BPD). Some of these individuals suffer from disorganized attachment and failed to develop a robust mentalization capacity. Fonagy and Bateman define mentalization as the process by which we implicitly and explicitly interpret the actions of oneself and others as meaningful on the basis of intentional mental states. The object of treatment is that patients with BPD increase their mentalization capacity, which should improve affect regulation, thereby reducing suicidality and self-harm, as well as strengthening interpersonal relationships.

More recently, a range of mentalization-based treatments, using the "mentalizing stance" defined in MBT but directed at children (MBT-C), families (MBT-F) and adolescents (MBT-A), and for chaotic multi-problem youth, AMBIT (adaptive mentalization-based integrative treatment) has been under development by groups mainly gravitating around the Anna Freud National Centre for Children and Families.

The treatment should be distinguished from and has no connection with mindfulness-based stress reduction (MBSR) therapy developed by Jon Kabat-Zinn.