Although it has been more than 40 years since "health for all" was presented as a focus in the Alma Ata declaration [1], the world is still far from achieving this goal. Although great progress has been made since then in many areas of health, much of that progress has been confined to rich countries, and even within the richest of countries, health inequality persists. New health problems and threats have arisen in the generations since that hopeful statement, with the scourge of HIV and the challenge of non-communicable diseases (NCDs) facing high and low-income countries alike [2]. With these new challenges, we see inequalities forming along the same old social fault lines and the same axes of deprivation and discrimination. In high-income countries, new risk factors such as obesity and food insecurity cluster in the poorest communities [3,4], while on a global level, we see the greatest burden of new diseases such as HIV falling on the poorest countries [5], and continuing challenges of health access and financing for the poorest people [6]. Much of this inequality arises from simple economic inequality and the consequences of colonialism, but much also results from the marginalization of certain individuals and groups at community, national and global levels. Sexual minorities, people with mental illness, migrants, refugees, the homeless, transient populations, transgender people, sex workers and many other groups who do not conform to existing social norms, or who have historically been marginalized and excluded, experience many often completely preventable illnesses. Discrimination against some members of the community, their exclusion from economic, cultural and social processes, and the selective provision of basic services to these communities put them at increased risk of poor health and expose them to preventable risk factors. Because the marginalization of these people is socially and historically determined, the health consequences for these people continue to be severe and pernicious, despite being preventable.In this Special Issue on the health of marginalized people, we have gathered 15 papers from many countries, describing a wide range of physical and mental health issues, using a variety of advanced research methods to understand the health challenges faced by a diverse array of marginalized populations globally, and recommending interventions to improve the health of marginalized populations. First, we summarize the research articles presented in this Special Issue and then issue a call for renewed action to end discrimination and marginalization in our societies, and to strengthen wider efforts to support the health of the most marginalized people.Mental health and suicide are significant issues among marginalized populations which do not receive sufficient attention. In this issue, Gilmour et al. [7] describe the suicide mortality rates of foreigners living in Japan compared with those in their country of origin and in Japanese nationals. They showed that, distinct from other nationalities...