Recognition of the limitations of the current categorical diagnostic system and increased understanding of commonalities across clinical problems associated with negative emotion, including anxiety and depression, has led to the development of transdiagnostic psychological interventions. This new approach holds promise in shifting our emphasis from diagnostic categories to treating core construct that cut across disorders. This paper identifies some of the similarities and differences across various cognitive-behavioral transdiagnostic protocols and key challenges in assessment and case conceptualization for clinicians wishing to use this approach. Some key needs in the research literature that would be particularly helpful to clinicians are also identified. (C) 2016 Elsevier Ltd. All rights reserved.