1 Foundations of Public Health and Population Health

Public health as collective action

Public health is society’s organized, collective work to create the conditions in which people can be healthy. It includes work by government, health care, community organizations, businesses, schools, and other partners—not just services delivered by health departments. Government has a distinctive responsibility to protect the public, including through laws and regulations.

Population health and its distribution

Population health describes the health outcomes of a group, how those outcomes are distributed within the group, and the determinants and policies that influence them. A population may be defined by place, age, occupation, or another shared characteristic. Considering both overall outcomes and their distribution can reveal whether some groups experience systematically worse health.

Public health and population health are closely related but emphasize different things. Population health focuses on outcomes, their distribution, and contributing factors; public health emphasizes the collective practice and systems used to protect and improve health.

For example, comparing asthma rates across neighborhoods takes a population-health perspective. Coordinating air-quality monitoring, community outreach, and policies to reduce exposure is public-health practice.

The core functions

The core functions of public health are assessment, policy development, and assurance. Together, they organize how public health work identifies needs, shapes responses, and helps put those responses into practice.

1. Assessment: Gather and analyze information about health, health risks, community needs, and available resources.

2. Policy development: Use evidence and community input to establish priorities, develop plans, and create policies that support health.

3. Assurance: Help ensure that effective services and protections are available, the workforce is capable, and public health activities are evaluated.

The functions are interconnected: assessment identifies a problem, policy development shapes a response, and assurance helps implement the response and check whether it works.

The 10 Essential Public Health Services

The 10 Essential Public Health Services make the core functions more concrete. The revised framework centers equity and describes activities communities should carry out:

1. Assess and monitor population health status, factors that influence health, and community needs and assets.

2. Investigate, diagnose, and address health problems and hazards affecting the population.

3. Communicate effectively to inform and educate people about health, factors that influence it, and how to improve it.

4. Strengthen, support, and mobilize communities and partnerships to improve health.

5. Create, champion, and implement policies, plans, and laws that impact health.

6. Utilize legal and regulatory actions designed to improve and protect the public’s health.

7. Assure an effective system that enables equitable access to the individual services and care needed to be healthy.

8. Build and support a diverse and skilled public health workforce.

9. Improve and innovate public health functions through ongoing evaluation, research, and continuous quality improvement.

10. Build and maintain a strong organizational infrastructure for public health.

The services work together rather than as isolated tasks. For example, when a health department detects an increase in measles cases, it can investigate the outbreak, communicate guidance, coordinate with health care providers and community partners, support vaccination access, and evaluate whether the response is limiting further spread.

Practice, partnerships, and progress

Public health practice applies evidence, professional expertise, and community partnership to protect and improve health across populations. Practitioners may monitor health trends, investigate hazards, communicate risks, support community-led efforts, advise policymakers, enforce health protections, connect people to needed services, and evaluate programs. This work often crosses organizational boundaries because conditions and decisions beyond the health sector also influence health.

A central aim is to improve health while attending to who benefits and who may be left behind. Population-level measures can show whether outcomes are changing overall; examining results across groups can show whether gaps persist or widen. Public health practice uses both kinds of information to guide action and assess progress.