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Social Ecological Model

The Social Ecological Model (SEM) is a theoretical framework for understanding the factors that influence health and wellness at varying levels surrounding individuals, groups, and populations.

Although numerous variations of the SEM are in use throughout many areas of research including public health, the most commonly used framework is an adaptation of the research by Urie Bronfenbrenner. Bronfenbrenner’s Ecocological Systems Theory describes the broadening layers of influence over individuals’ behavior from “micro” to “macro.”

The Health Equity Toolkit includes a basic version of the SEM developed from a combination of Bronfenbrenner’s model and additional psychological and public health research. This model is applicable to health promotion practice and describes factors that influence health at the individual, interpersonal, organizational, community, and systems levels.

Interventions to combat obesity disparities may take place at all levels of the SEM. The Health Equity Toolkit, however, emphasizes programs implemented at the outermost levels of the SEM.

Scroll over the different levels of the SEM model below for examples of obesity programs!

This model is a visual representation of the Social Ecological Framework (SEM).  The inner most circle of this stacked Venn diagram symbolizes the individual or most base level of the SEM; and from there widening circles evolve to indicate the remaining the levels : interpersonal, institutions and organizations, community, and finally the structures and systems level. As an additional function, this model also provides examples of programmatic activities which correspond to specific levels of the SEM when the user positions their mouse pointer over each corresponding circle.

Structures and Systems: Structural changes are made toward the development of safe parks, recreational areas, and sidewalks statewide to help facilitate physical activity.

Community: In a town with disproportionately low access to fresh fruits and vegetables, a working group of local school officials, community leaders, and business owners help establish an open food cooperative as well as a biweekly farmers market.

Institutions and Organizations: A private business park replaces fast food and soft drink options in the cafeteria with water, fresh sandwiches, and salad bars to encourage employees to replace unhealthy options with more vegetables and water.

Interpersonal: Peer support groups, recipe swaps, and walking groups encourage members to keep each other accountable to nutrition and activity goals. Here programs utilize relationships between individuals and social support networks to influence change.

Individual: A social media campaign to educate adolescents and young adults about the benefits of regular moderate activity. Here a practitioner endeavors to increase the target population’s knowledge, and subsequently help form positive attitudes toward physical activity.

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The primary circle of the SEM represents the individual ultimately affected by all other levels of the SEM. Individual level factors influencing health include behaviors, knowledge, attributions, and beliefs.


The next tier in the SEM represents individuals’ interactions with one another, or relationships shared within social networks such as families, peer groups, and friendship-based social networks

Institutions and Organizations

This tier represents policies and rules specific to assemblies of individuals and their relationships. Common examples of assemblies include schools, religious or faith-based institutions, and the workplace.


Communities can be described as a larger societal construct comprised, in varying combinations, of the three smaller tiers of the SEM. Communities are composed of individuals as they participate in interpersonal relationships within various groups of institutions and organizations. Communities may be defined geographically, politically, culturally, or by other common characteristics.

Structures and Systems

This outermost tier of the SEM represents the local, state, and federal structures and systems which affect the built environment surrounding communities and individuals.

Additional SEM Resources

For additional reading, check out these publications:

  • Bronfenbrenner, U. (1977). Toward an experimental ecology of human development.” American Psychologist, 32: 513-531.
  • Bronfenbrenner, U. (1979). The Ecology of Human Development. Cambridge, Massachusetts, Harvard University Press.
  • McLeroy, K., Bibeau, D., Steckler, A., & Glanz, K. (1988). An ecologic perspective on health promotion programs. Health Education Quarterly, 15: 351-377.
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