Mental healthcare respecting human rights is a worldwide need, yet research into practices that support such rights is limited. The United Nations Convention on the Rights of Persons with Disabilities, 2006 and the United Nations Resolution on mental health and psychosocial support, 2023 each heighten the urgency and the legal, as well as moral, social, political and other obligations to improve the quality of mental healthcare and respect human rights worldwide. It is useful to be specific about the actions to be taken, as done in recent programmes by the World Psychiatric Association and the World Health Organization. The work requires partnerships at all levels, from global to local, among healthcare professionals, people with lived experience and their families, communities and policy-makers. We present a themed series of papers developed in two parts: one related to principles of human rights-based mental healthcare; the other to assessment, policy and actions needed for tackling the implementation gap.