Work and mental health: what do we know and how can we intervene? As working conditions are increasingly characterized by socio-emotional demands, interpersonal interactions and relationships, and mental requirements, at least in high-income, post-industrialized societies, work and mental health has evolved as a key topic of occupational health research (1, 2). In this editorial, we focus on three main themes within this topic: (i) identifying factors at work that contribute to the onset of mental health problems and clinical mental disorders; (ii) using work as a "therapeutic tool" for individuals with mental health problems; and (iii) conducting and evaluating intervention studies. Regarding the first theme, one of the earliest systematic reviews on work-related risk factors of common mental disorders was published in 2006 by Stansfeld & Candy in this journal (3), an article that today is a "citation classic" (876 citations in Web of Science as of 6 October 2019). The authors identified job strain and effort-reward imbalance as risk factors, while acknowledging that only few studies of high quality were available (3). Today, more high quality studies are available and recent meta-analyses reported that job strain (4) and effort-reward imbalance (5) predict incident depressive disorders, corroborating the conclusion of the pioneering 2006 review. Other reviews suggest that also low job control (6), workplace bullying (6), and job insecurity (7) may be involved in the etiology of depressive disorders. Long working hours are also discussed, however, a recent review reported that associations between long working hours and depressive symptoms were relatively small and differed between world regions (8). Currently, the World Health Organization (WHO) and the International Labour Organization (ILO) are working on parameters for estimating the global burden of depressive disorders attributable to long working hours (9). Despite this progress in research, important challenges remain, for example the overreliance on traditional cohort studies with one baseline and one follow-up measure only, and on self-reported measures of working conditions that may be affected by undetected prevalent mental health problems (10). Recent studies, using multiple exposure measures with fixed-effects analyses (11) or job exposure matrices (12) have started to address these challenges. Further, more research is needed on mental disorders other than depressive disorders, such as anxiety or adjustment disorders (10). Regarding the second theme-work as a therapeutic tool-a key publication was the report by Dame Carol Black for the British Government in 2008 on "Working for a healthier tomorrow" (13). 1 The report argued that "work which is appropriate to an individual's knowledge, skills and circumstances, and undertaken in a safe, healthy and supportive working environment, promotes good physical and mental health, helps to prevent ill-health and can play an active part in helping people recover from illness" (13, p67). Results from observat...