This study explored whether and how internal representations of adolescents' relationship with their parents--a fundamental concept in psychodynamic theory--changed in the course of a year of treatment and whether the observed changes were related to changes in symptoms. Seventy two adolescents (ages 15-18; 30 in treatment and 42 in a non-treatment "community group") underwent Relationship Anecdote Paradigm (RAP) interviews according to the Core Conflictual Relationship Theme method (CCRT; Luborsky & Crits-Christoph, 1998) and completed outcome measures at two time points. A novel data-driven approach to clustering CCRT categories was used to characterize internal representations. The potential contribution of this approach to the CCRT method is discussed. The results indicate that adolescents' internal representations of their relationships with their parents changed significantly throughout treatment, and were related to changes in symptoms.