Localism is a range of political philosophies which prioritize the local. Generally, localism supports local production and consumption of goods, local control of government, and promotion of local history, local culture and local identity. Localism can be contrasted with regionalism and centralized government, with its opposite being found in unitarism.

Localism can also refer to a systematic approach to organizing a central government so that local autonomy is retained rather than following the usual pattern of government and political power becoming centralized over time.

On a conceptual level, there are important affinities between localism and deliberative democracy. This concerns mainly the democratic goal of engaging citizens in decisions that affect them. Consequently, localism will encourage stronger democratic and political participatory forums and widening public sphere connectivity.

Localists assert that throughout the world's history, most social and economic institutions are scaled at the local level, as opposed to regional, interregional, or global . Through ongoing forms of colonialism, imperialism and industrialisation local scales become less central. Most proponents of localism position themselves as defending aspects of this way of life; the phrase "relocalization" is often used in this sense.

In the 20th century, localism drew heavily on the writings of Leopold Kohr, E. F. Schumacher, Wendell Berry, and Kirkpatrick Sale, among others. More generally, localism draws on a wide range of movements and concerns and it proposes that by re-localizing democratic and economic relationships, social, economic and environmental problems will be more definable and solutions more easily created. They include anarchism, bioregionalism, environmentalism, the Greens, and more specific concerns about food, monetary policy and education. Political parties of all persuasions have also occasionally favored the devolution of power to local authorities. In this vein Alan Milburn, a UK Labour Party MP, has spoken of "making services more locally accountable, devolving more power to local communities and, in the process, forging a modern relationship between the state, citizens and services"

Beginning in the 1960s, a particularly visible strain of localism in the United States was a movement started by Alice Waters to buy locally produced products. This movement originated with organic farming and likely gained impetus because of growing dissatisfaction with organic certification and the failing economic model of industrial agriculture for small farmers. While the advocates of local consumption draw on protectionist arguments, they also appealed primarily to an environmental argument: that pollution caused by transporting goods was a major externality in a global economy, and one that "localvores" could greatly diminish. Also, environmental issues can be addressed when decision-making power is held by those affected by the issues instead of power sources that do not understand the needs of local communities.

Localism as a philosophy is related to the principle of subsidiarity.

In the early 21st century, localists have frequently found themselves aligned with critics of globalisation. Variants of localism are prevalent within the Green movement. According to an article in International Socialism, localism of this sort seeks to "answer to the problems created by globalisation" with "calls to minimise international trade and to seek to establish economies based on ‘local’ self-sufficiency only."