The Confederación Nacional del Trabajo (CNT; lit. 'National Confederation of Labor') is a Spanish anarcho-syndicalist trade union confederation.

Founded in 1910 in Barcelona from groups brought together by the trade union Solidaridad Obrera, it significantly expanded the role of anarchism in Spain, which can be traced to the creation of the Spanish chapter of the IWA in 1870 and its successor organization, the Federation of Workers of the Spanish Region. Despite several decades when the organization was illegal in Spain, the CNT continues to participate in the Spanish worker's movement, focusing its efforts on the principles of workers' self-management, federalism, and mutual aid.

Historically affiliated with the International Workers' Association (AIT), in 2018, the CNT and other unions founded the International Confederation of Labour (ICL-CIT).

The CNT says of its membership, "We make no distinction at the time of admission, we require only that you are a worker or a student, employed or unemployed. The only people who cannot join are those belonging to repressive organizations (police, military, security guards), employers or other exploiters".

As a union organization, and in accordance with its bylaws, the aims of the CNT are to "develop a sense of solidarity among workers", hoping to improve their conditions under the current social system, prepare them for future emancipation, when the means of production have been socialized, to practice mutual aid amongst CNT collectives, and maintain relationships with other like-minded groups hoping for emancipation of the entire working class. The CNT is also concerned with issues beyond the working class, desiring a radical transformation of society through revolutionary syndicalism. To achieve their goal of social revolution, the organization has outlined a social-economic system through the confederal concept of anarchist communism, which consists of a series of general ideas proposed for the organization of an anarchist society. The CNT draws inspiration from anarchist ideas, and also identifies with the struggles of different social movements. The CNT is internationalist, but also supports communities' right of self-determination and their sovereignty over the state.

The CNT is rooted in three basic principles: workers' self-management or autogestión, federalism and mutual aid, and considers that work conflicts must be settled between employers and employees without the action of such intermediaries as official state organisms or professional unionists. This is why the union criticizes union elections and works councils as means of control for managers, preferring workers' assemblies, union sections and direct action. Also, when possible, the CNT avoids taking legal action through the courts. Administrative positions in the union rotate and are unpaid.

The organizational structure of the CNT is based on direct democracy.

The industrial unions (sometimes referred to as "branch unions") form the base structure of the CNT. Each industrial union groups together workers of different crafts within an industry. When there are fewer than 25 people working in one particular industry, a various posts union is formed for that industry, rather than multiple industry unions. A various posts union can include workers from different crafts and industries; it requires a minimum of five people. If this number cannot be reached, four or fewer workers can form a confederal group. Due to the small size of the CNT, a majority of its unions are various posts unions.