Background: The size and increasing burden of disease due to mental disorders in Europe poses substantial challenges to its population and to the health policy of the European Union. This warrants a specific research agenda concerning clinical mental health research as one of the cornerstones of sustainable mental health research and health policy in Europe. The aim of this research was to identify the top priorities needed to address the main challenges in clinical research for mental disorders. Methods: The research was conducted as an expert survey and expert panel discussion during a scientific workshop. Results: Eighty-nine experts in clinical research and representing most European countries participated in this survey. Identified top priorities were the need for new intervention studies, understanding the diagnostic and therapeutic implications of mechanisms of disease, and research in the field of somatic-psychiatric comorbidity. The "subjectivity gap" between basic neuroscience research and clinical reality for patients with mental disorders is considered the main challenge in psychiatric research, suggesting that a shift in research paradigms is required. Conclusion: Innovations in clinical mental health research should bridge the gap between mechanisms underlying novel therapeutic interventions and the patient experience of mental disorder and, if present, somatic comorbidity. Clinical mental health research is relatively underfunded and should receive specific attention in Horizon 2020 funding programs.