Justice is central to the mission of public health, but what does social justice require for the public's health? The account of justice here stresses the fair disbursement of common advantages and the sharing of common burdens. It captures the twin moral impulses that animate public health: to advance human well-being by improving health and to do so by focusing on the needs of the most disadvantaged. Social justice measures would soften some of the most egregious inequities in health care. The federal government should invest in a strong public health system and be prepared to respond to threats that may transcend state borders, the authors argue. The concept also highlights the need for governmental action to address the major causes of ill health, particularly among the disadvantaged. This will often require overlapping and shared responsibility among federal, state and local governments. In general, the justice perspective would place as much value on the public good as on personal and economic liberty, and view the public good as involving a commitment to the health and equal worth of all members of the community.