This article describes a case formulation-driven approach to cognitive-behavior therapy (CBT) that draws on the formulations and interventions in the ESTs while helping the therapist make many of the clinical decisions that are not directly addressed in the ESTs. We begin the article with an overview of case formulation-driven CBT. Then we describe each of the steps of case formulation-driven CBT, giving special attention to the step of developing a case formulation. We conclude with a brief discussion of alternate approaches to case formulation in CBT, and a brief review of evidence supporting the use of a case formulation approach to CBT.