Despite the publication of high-profile reports and promising activities in several countries, progress in mental health service development has been slow in most low-income and middle-income countries. We reviewed barriers to mental health service development through a qualitative survey of international mental health experts and leaders. Barriers include the prevailing public-health priority agenda and its effect on funding; the complexity of and resistance to decentralisation of mental health services; challenges to implementation of mental health care in primary-care settings; the low numbers and few types of workers who are trained and supervised in mental health care; and the frequent scarcity of public-health perspectives in mental health leadership. Many of the barriers to progress in improvement of mental health services can be overcome by generation of political will for the organisation of accessible and humane mental health care. Advocates for people with mental disorders will need to clarify and collaborate on their messages. Resistance to decentralisation of resources must be overcome, especially in many mental health professionals and hospital workers. Mental health investments in primary care are important but are unlikely to be sustained unless they are preceded or accompanied by the development of community mental health services, to allow for training, supervision, and continuous support for primary care workers. Mobilisation and recognition of non-formal resources in the community must be stepped up. Community members without formal professional training and people who have mental disorders and their family members, need to partake in advocacy and service delivery. Population-wide progress in access to humane mental health care will depend on substantially more attention to politics, leadership, planning, advocacy, and participation.