Initially developed by Karl Deutsch and his co-authors in their 1957 study Political Community and the North Atlantic Area. Put most simply, a security community exists when a group of states have forged a sense of community or collective identity, meaning they will settle their differences without resorting to force. A security community is not the same as an alliance or a collective defence grouping, although security communities can potentially grow out of and co-exist with these kind of military relationships.

Deutsch identified two distinct categories of security communities: amalgamated and pluralistic. An amalgamated security community exists when there is a “formal merger of two or more previously independent units into a single larger unit, with some type of common government after amalgamation”. An example would be the United States, in which the fifty states have united under a single federal government. In a pluralistic security community, by contrast, the members of the community “retain the legal independence of separate governments.” Examples of a pluralistic security community include the relationship between the United States and Canada, Western Europe, and the Baltic States region.

Most applications of Deutsch's concept assume that a security community must meet several requirements. The first, and most important, is there must be a total absence of armed conflict, or prospects for such a conflict among the members who make up the community. This is not to suggest that these states will be without disagreements or disputes. Rather, it means some way has been found to prevent the governments involved from resorting to the use or threat of force. According to Deutsch, the community of states must share “dependable expectations of peaceful change” in their mutual relations and rule out the use of force as a means of problem solving.

A second, and closely related, requirement for a security community is the absence of a competitive military build-up or arms race involving community members.