In emergency services, mutual aid is a formal agreement among emergency responders to lend assistance across jurisdictional boundaries when required; either by an emergency that exceeds local resources or a disaster. On a smaller scale the principle of mutual aid guides the creation of militia and community emergency response teams, e.g. volunteer fire fighters.

In political economy, mutual aid is a term which describes a principle central to libertarian socialism or anarchism, and is used to signify the economic concept of voluntary reciprocal exchange of resources and services for mutual benefit.

In his book, Governing Local Public Economies, Ronald J. Oakerson states, "Mutual aid is used to solve two important problems:

1. problems that cross jurisdictional boundaries
2. peak-load problems created by occasional extreme demands on service capacity

The driving force behind coordination is self-interested reciprocity, which can operate without a legally binding agreement."

As a concept it was developed and advanced by the anarcho-communist Peter Kropotkin. In his book Mutual Aid: A Factor in Evolution, Kropotkin explored the utility of cooperation as a survival mechanism for animals, in order to counteract the conception of evolution as a fierce competition for survival between individuals that provided a rationalization for the theories of Social Darwinism. His observations of indigenous peoples in Siberia guided him to conclude that not all human societies were so competitive as Europe's.

In another of his books, The Conquest of Bread, Kropotkin proposed a system of economics based on mutual exchanges made in a system of voluntary cooperation. Kropotkin's thesis was based on the premise that scarcity was unnecessary, and it was possible to produce enough wealth to satisfy the needs of everybody by working only five hours a day during adult life (leaving the rest of the day to satisfy desires for luxuries, if so desired), but that flawed economic systems had led to inefficient allocation of resources which prevented this bounty from being achieved.

In Fields, Factories and Workshops Tomorrow , Kropotkin, a geographer by training, gives a detailed accounting of the physical evidence for his claim that the earth was fully capable of satisfying the resource needs of all its citizens with a minimum of work.

However, Kropotkin never fully outlined how such a system would be achieved, nor did he answer the questions of how such a system would be structured or make decisions, other than to make vague pronouncements about mutual exchanges (e.g., he gives the examples of farmers in the countryside producing grain for the city based on the understanding that workers in the city will then provide them with finished goods).

See also: political science