In the UK, recent guidelines on the treatment of depression and anxiety recommend CBT-based self-help materials as one important component of services. However, despite being based on specific CBT techniques or "empirically grounded interventions", early optimism has been dented by data from recent studies that have cast doubt on the effectiveness of the current generation of these materials. As a consequence, it may be necessary to consider that other factors may contribute to the overall magnitude of CBT effects. Indeed, it is logically inconsistent to argue that specific factors are pre-eminent in CBT whilst maintaining that delivery via therapists is more likely to be effective than self-help. The contribution of "common factors" that operate in personal therapeutic encounters, for example, therapist responsiveness and the patient-therapist alliance, may be one possible overlooked reason for the reduced ef-fectiveness of self-help materials. The development of the next generation of self-help materials, therefore, may benefit from the testing of materials that combine common and specific factors, including specific measurement of the strength of common factors and their relationship to clinical outcomes. We discuss a model of such common factors and suggest how they could be incorporated into the next generation of CBT based self-help materials.