Psychotherapy integration has recently received considerable attention among behavior therapists. Although the wisdom of ecumenicism has been questioned, behavior therapy has often been credited with flexibility and modification of practice based on experimental and clinical research. From this perspective, the two central criteria for psychotherapy integration are inclusion of proven therapeutic elements and exclusion of unproven ones. Rationales for the importance of both criteria are discussed, and an analogy to the development of modern medicine is suggested. Formal acceptance of the proposed criteria would place psychotherapy integration in a proactive position to censor fee-for-service clinical practice not grounded in basic clinical or experimental research.