This is a time of unprecedented interest in the field of global mental health. Since the WHO World Mental Health Report of 2001 (World Health Organization, 2001) there has been an accelerating tempo of evidence and initiatives. These show an appreciation of the scale of the mental health gap across all of the world (Wang et al. Reference Wang, Aguilar-Gaxiola, Alonso, Angermeyer, Borges, Bromet, Bruffaerts, de Girolamo, de Graaf, Gureje, Haro, Karam, Kessler, Kovess, Lane, Lee, Levinson, Ono, Petukhova, Posada-Villa, Seedat and Wells2007; Thornicroft et al. Reference Thornicroft, Chatterji, Evans-Lacko, Gruber, Sampson, Aguilar-Gaxiola, Al-Hamzawi, Alonso, Andrade, Borges, Bruffaerts, Bunting, de Almeida, Florescu, de Girolamo, Gureje, Haro, He, Hinkov, Karam, Kawakami, Lee, Navarro-Mateu, Piazza, Posada-Villa, de Galvis and Kessler2017), and demonstrate the strengthening evidence base of effective interventions to treat people with mental illnesses in low and middle income countries (LMICs) (Patel & Thornicroft, Reference Patel and Thornicroft2009; Patel et al. Reference Patel, Chisholm, Parikh, Charlson, Degenhardt, Dua, Ferrari, Hyman, Laxminarayan, Levin, Lund, Medina Mora, Petersen, Scott, Shidhaye, Vijayakumar, Thornicroft and Whiteford2016; Petersen et al. Reference Petersen, Evans-Lacko, Semrau, Barry, Chisholm, Gronholm, Egbe and Thornicroft2016; World Health Organisation., 2016).

In terms of the inter-related elements necessary to strengthen health systems (including primary care, community care and specialist care) in providing treatment to people with mental illness, one aspect that has been relatively neglected is the need to provide actionable and sustained training to staff (Thornicroft et al. Reference Thornicroft, Cooper, Bortel, Kakuma and Lund2012). This edition of Epidemiology and Psychiatric Sciences includes three papers that address this issue. The Editorial by Semrau et al. outlines capacity-building approaches and outputs to support mental health system strengthening for three target groups (i) mental health service users and caregivers, (ii) service planners and policy-makers, and (iii) mental health researchers) in six LMICs in Sub-Saharan Africa and in Asia (Ethiopia, India, Nepal, Nigeria, South Africa and Uganda).

The second paper by Hanlon et al. focuses on the methods, which can be used to evaluate the impact of such capacity-building in these three target groups. Third, the paper by Lempp et al. reports on a cross-country qualitative study of in-depth interviews with service users and caregivers to assess their involvement in mental health system strengthening. This is important because service user involvement in any aspect of mental health care planning, provision or evaluation is still in its infancy in many LMICs (Thornicroft & Tansella, Reference Thornicroft and Tansella2005), although in several countries this is now gaining pace (Samudre et al. Reference Samudre, Shidhaye, Ahuja, Nanda, Khan, Evans-Lacko and Hanlon2016; Abayneh et al. Reference Abayneh, Lempp, Alem, Alemayehu, Eshetu, Lund, Semrau, Thornicroft and Hanlon2017; Gurung et al. Reference Gurung, Upadhyaya, Magar, Giri, Hanlon and Jordans2017).

These papers arise from the EU-funded Emerald (Emerging mental health systems in low- and middle-income countries) programme, which is investigating mental health system strengthening in these six countries (see www.emerald-project.eu) (Semrau et al. Reference Semrau, Evans-Lacko, Alem, Ayuso-Mateos, Chisholm, Gureje, Hanlon, Jordans, Kigozi, Lempp, Lund, Petersen, Shidhaye and Thornicroft2015) alongside financial equity (Chisholm et al. Reference Chisholm, Heslin, Docrat, Nanda, Shidhaye, Upadhaya, Jordans, Abdulmalik, Olayiwola, Gureje, Kizza, Mugisha, Kigozi, Hanlon, Adugna, Sanders, Pretorius, Thornicroft and Lund2017), integrated care (Petersen et al. Reference Petersen, Marais, Abdulmalik, Ahuja, Alem, Chisholm, Egbe, Gureje, Hanlon, Lund, Shidhaye, Jordans, Kigozi, Mugisha, Upadhaya and Thornicroft2017) and establishing mental health system indicators (Jordans et al. Reference Jordans, Chisholm, Semrau, Upadhaya, Abdulmalik, Ahuja, Alem, Hanlon, Kigozi, Mugisha, Petersen, Shidhaye, Lund, Thornicroft and Gureje2016; Upadhaya et al. Reference Upadhaya, Jordans, Abdulmalik, Ahuja, Alem, Hanlon, Kigozi, Kizza, Lund, Semrau, Shidhaye, Thornicroft, Komproe and Gureje2016).

An important part of the legacy of Emerald is the development of 27 Masters-level teaching modules, and three short courses on mental health system strengthening (for service users and caregivers; policy-makers and planners; and mental health researchers), in addition to having provided support for pre- and post-doctoral research staff, These teaching packages will be made available under a Creative Commons open access license in the near future via the Emerald website at King's College London. The capacity-building approaches taken by Emerald may serve as a model to be adapted for other LMICs for future initiatives designed to support knowledge, attitude and skill enhancement for everyone concerned with mental health system strengthening in LMICs.