The main goals of the proposed study are to establish the psychometric properties of the Therapy Process Observational Coding System for Child Psychotherapy (TPOCS) and to assess applications of the TPOCS to the study of therapy process and outcome. The TPOCS is being developed to measure specific (e.g., therapeutic interventions) and nonspecific (e.g., therapeutic alliance) process variables that are prominent in child psychotherapy but for which observational assessment has not been well-developed to date. Development of the TPOCS will provide the field with a new research tool to quantify theoretically important processes in child psychotherapy and to assess proposed mediators of child psychotherapy outcome. The psychometric properties of the TPOCS will be assessed using a sample of treatment-as-usual psychotherapy tapes drawn from a larger ongoing study. Once the psychometric properties of the TPOCS are established, the TPOCS scales will be used to investigate three key questions of theoretical interest in therapy process research: (a) Are some therapy processes (i.e., specific and non-specific) associated with therapy engagement? (b) Do some therapy processes predict changes in children?s post-treatment outcomes? (c) Are the linkages between therapy processes and children?s posttreatment outcomes mediated by therapy engagement?