Laissez-faire ( LESS-ay-FAIR; from French: laissez faire [lɛse fɛʁ] (listen), lit. 'let do') is a type of economic system in which transactions between private groups of people are free from any form of economic interventionism (such as subsidies or transfer payments). As a system of thought, laissez-faire rests on the following axioms: "the individual is the basic unit in society, i.e. the standard of measurement in social calculus; the individual has a natural right to freedom; and the physical order of nature is a harmonious and self-regulating system."

Another basic principle of laissez-faire holds that markets should naturally be competitive, a rule that the early advocates of laissez-faire always emphasized. With the aims of maximizing freedom by allowing markets to self-regulate, early advocates of laissez-faire proposed a impôt unique, a tax on land rent (similar to Georgism) to replace all taxes that they saw as damaging welfare by penalizing production.

Proponents of laissez-faire argue for a near complete separation of government from the economic sector. The phrase laissez-faire is part of a larger French phrase and literally translates to "let [it/them] do", but in this context the phrase usually means to "let it be" and in expression "laid back". Although never practiced with full consistency, laissez-faire capitalism emerged in the mid-18th century and was further popularized by Adam Smith's book The Wealth of Nations.

While associated with capitalism in common usage, there are also non-capitalist forms of laissez-faire, including some forms of market socialism.