A common factor linked to recovery in a variety of psychotherapies is mentalizing, the fundamental human ability to understand oneself and others in terms of intentional mental states, such as feelings, desires, attitudes, and goals. Psychotherapy interventions that promote mentalization are also linked to positive outcomes. The adoption of mentalization-based interventions for children has been somewhat slow, despite their potential. Moreover, when compared to the evidence-base for mentalization-based interventions for infants or adults, middle childhood currently lacks a well-developed body of research supporting mentalization-based interventions. The studies depicted in this paper aim to address this gap, elucidating the kinds of mentalization-based interventions and their assessments that are being conducted at Istanbul Bilgi University Psychotherapy Center. These studies have the aim of not only assessing the effectiveness of mentalization-based interventions with school-age children, but also identifying why and how these interventions work, meaningfully linking clinical process with outcome.