The WHO was established on 7 April 1948. The first meeting of the World Health Assembly (WHA), the agency's governing body, took place on 24 July of that year. The WHO incorporated the assets, personnel, and duties of the League of Nations' Health Organization and the , including the International Classification of Diseases (ICD). Its work began in earnest in 1951 after a significant infusion of financial and technical resources.
The WHO's mandate seeks and includes: working worldwide to promote health, keeping the world safe, and serve the vulnerable. It advocates that a billion more people should have: universal health care coverage, engagement with the monitoring of public health risks, coordinating responses to health emergencies, and promoting health and well-being. It provides technical assistance to countries, sets international health standards, and collects data on global health issues. A publication, the ''World Health Report'', provides assessments of worldwide health topics. The WHO also serves as a forum for discussions of health issues.
The WHO relies on contributions from member states (both assessed and voluntary) and private donors for funding. Its total approved budget for 2020–2021 is over $7.2 billion, of which the majority comes from voluntary contributions from member states. Contributions are assessed by a formula that includes GDP per capita. Among the largest contributors were Germany (which contributed 12.18% of the budget), the Bill & Melinda Gates Foundation (11.65%), and the United States (7.85%).
Since the late 20th century, the rise of new actors engaged in global health such as the World Bank, the Bill & Melinda Gates Foundation, the US President's Emergency Plan for AIDS Relief (PEPFAR) and dozens of public-private partnerships for global health have weakened the WHO’s role as a coordinator and policy leader in the field.