This article describes the Clinical Outcomes in Routine Evaluation (CORE) System and reports on its scientific yield and practice impact. First, we describe the suite of CORE measures, including the centerpiece CORE-Outcome Measure (CORE-OM), its short forms, special purpose forms, translations, and psychometric properties, along with the pretreatment CORE Therapy Assessment Form and the CORE End of Therapy Form. Second, we provide an overview of the scientific yield arising from analyses of large CORE data sets collected in routine practice. Third, we describe the use of CORE measures for feedback in practice settings. Finally, we consider future directions for monitoring and feedback in research and practice.