Public health in the United States is guided by a set of three principles known as the Core Functions of Public Health.  The three Core Functions (assessment, policy development, and assurance) define the roles of federal, state and local public health systems. All public health agencies are responsible for assessing the status of public health in their communities, developing policies to address public health needs, and assuring public health needs are met.

Historically, public health professionals have worked largely behind-the-scenes to improve the health and safety of American communities. Today, public health and its leaders are in the spotlight. Strengthening public health systems and organizations is an enterprise of unprecedented interest. We in public health must capitalize on this interest by seeking new opportunities to assess and improve the ways we deliver public health services in our states and our communities.

The Core Functions and Essential Public Health Services provide the fundamental framework for the National Public Health Performance Standards Program (NPHPSP), by describing the public health activities that should be undertaken in all communities. The Core Public Health Functions Steering Committee developed the framework for the Essential Services in 1994. This steering committee included representatives from US Public Health Service agencies and other major public health organizations. The Essential Services provide a working definition of public health and a guiding framework for the responsibilities of local public health systems.

Mobilizing for Action through Planning and Partnerships, MAPP, is a strategic health planning model developed by the National Association of City and County Health Officials, the Centers for Disease Control to compliment and support the National Public Health Performance Standards Program - The Core Functions and Ten Essential Services of Public Health. The skills sets of MAPP provide a framework for public health professionals to practice in accordance with the Core Functions and Ten Essential Services.