This section of the Public Health Classics series revisits groundbreaking contributions to public health, focusing on the Preamble to the Constitution of the World Health Organization (WHO). The Preamble, approved at the International Health Conference in New York on July 22, 1946, outlines the foundational principles of WHO's mission and jurisdiction. Frank P. Grad provides a modern commentary, highlighting the document's enduring relevance and its role in shaping contemporary international public health. The Preamble asserts that health is a fundamental right for all people, encompassing physical, mental, and social well-being. It emphasizes the interdependence of health, peace, and security, noting that unequal development in health promotion and disease control poses a common danger. The document calls for the extension of medical and psychological knowledge to all, the active cooperation of the public, and the provision of adequate health and social measures by governments. The Preamble also underscores the importance of primary health care and the need for intergovernmental cooperation and international initiatives to achieve global health goals. The Preamble's principles have been instrumental in guiding WHO's activities, including the eradication of smallpox and ongoing efforts to combat diseases like HIV/AIDS. The document's vision of "Health for All by the Year 2000" remains a significant goal, emphasizing the need for equitable distribution of health resources and the provision of primary health care services. The Preamble concludes by requiring member states to accept these principles and support WHO's cooperative initiatives to promote and protect the health of all peoples.This section of the Public Health Classics series revisits groundbreaking contributions to public health, focusing on the Preamble to the Constitution of the World Health Organization (WHO). The Preamble, approved at the International Health Conference in New York on July 22, 1946, outlines the foundational principles of WHO's mission and jurisdiction. Frank P. Grad provides a modern commentary, highlighting the document's enduring relevance and its role in shaping contemporary international public health. The Preamble asserts that health is a fundamental right for all people, encompassing physical, mental, and social well-being. It emphasizes the interdependence of health, peace, and security, noting that unequal development in health promotion and disease control poses a common danger. The document calls for the extension of medical and psychological knowledge to all, the active cooperation of the public, and the provision of adequate health and social measures by governments. The Preamble also underscores the importance of primary health care and the need for intergovernmental cooperation and international initiatives to achieve global health goals. The Preamble's principles have been instrumental in guiding WHO's activities, including the eradication of smallpox and ongoing efforts to combat diseases like HIV/AIDS. The document's vision of "Health for All by the Year 2000" remains a significant goal, emphasizing the need for equitable distribution of health resources and the provision of primary health care services. The Preamble concludes by requiring member states to accept these principles and support WHO's cooperative initiatives to promote and protect the health of all peoples.