CBT is recognised at the most successful non-pharmacological treatment for problem gamblers. However, debate surrounds the true efficacy of the approach especially in light of the inconsistency in which CBT is applied and reported. All too often research purporting to offer CBT frequently use a mixed models or integrative approaches. This leads to it being unclear which components are responsible for the therapeutic change. This paper will examine the evidence supporting Cognitive-Behavior Therapy (CBT) with problem gamblers. The core components of CBT, as used with problem gamblers, will be further highlighted and a comparison across published studies made. Data will be presented from the authors' own practice and compared against published data where CBT is the main treatment approach. A Cognitive-Behavioral model of problem gambling will be formulated. This model will be used to inform a unified CBT approach that will assist therapists when choosing to treat gamblers using CBT. It will be argued that this approach will offer a common person-centred formulation driven model of treatment that sticks to the fundamental principles of CBT.