Ricardian socialism is a branch of socialist thought that developed in Great Britain between the 1820s and 1840s. Its proponents drew on David Ricardo's economic theories, primarily the labor theory of value, to argue for a socialist critique of capitalism. They contended that because labor is the source of all value, the entire product of labor should belong to the laborer. The profits, rent, and interest collected by capitalists, landlords, and lenders were therefore considered "unearned incomes" unjustly taken from the workers. Though labeled "Ricardian," these thinkers did not form a cohesive school and often drew their ideas more directly from Adam Smith's formulation of the labor theory of value; the term reflects Ricardo's status as the dominant economist of the era in which their ideas flourished.

The most prominent Ricardian socialists were William Thompson, John Gray, Thomas Hodgskin, and John Francis Bray. They wrote during a period of significant social and economic turmoil in Britain following the Napoleonic Wars and the height of the Industrial Revolution, with their work providing an intellectual counterpart to the era's widespread movements for political and economic reform. The Ricardian socialists are seen as a transitional group between earlier utopian socialism and the later "scientific socialism" of Karl Marx, who studied their works. They combined the Utopian belief in peaceful, rational reform with a new emphasis on economic analysis, laying the groundwork for subsequent socialist theories of exploitation and the economic interpretation of history.

The first half of the 19th century in England was a period of intense focus on political and economic problems. The era saw major legislative reforms, including the repeal of the Combination Acts in 1824–25, the Reform Act 1832, the reform of the Poor Laws in 1834, and the repeal of the Corn Laws in 1846. These events were accompanied by widespread public debate and agitation, as well as investigations into factory conditions and prisons.

This "reforming energy" was fueled by the economic conditions that followed the peace of 1815. The end of the Napoleonic Wars brought a severe economic downturn to Britain's young and rapidly expanding industrial economy. The Industrial Revolution had transformed Britain from a farming to a manufacturing nation, but the post-war period was marked by a prolonged depression. Walter Bagehot noted that "for the thirty years succeeding the peace of 1815 England was always uncomfortable: trade was bad, employment scarce." These harsh conditions, combined with inhuman factory hours and working conditions, produced a generation of radical thinkers. While classical economists advocated for laissez-faire reforms, a counter-agitation emerged for communism and socialistic reorganization, inspired in part by the writings of the Ricardian socialists.

The Ricardian socialists were not a formal school of thought, but they shared a common line of economic reasoning that formed the basis of their social criticism. Although later scholarship labeled them "Ricardian," they primarily cited Adam Smith as the authority for their core economic principle, the labor theory of value. The term "Ricardian socialism" arose because David Ricardo was the most prominent figure in the classical school of economics where this theory was a central doctrine.

Their argument began with the premise that labor is the source of all wealth. As William Thompson stated, "Wealth is produced by labor: no other ingredient but labor makes any object of desire an object of wealth." From this, they derived their central ethical claim: the right of the laborer to the whole produce of their labor. They used this claim to analyze the existing distribution of wealth under capitalism. They concluded that the incomes of landlords and capitalists—rent, profit, and interest—were deductions from the produce of labor. These "unearned incomes" were viewed as an "exploitation" of the working class. Thomas Hodgskin argued, for instance, that "Capital is the product of labour, and profit is nothing but a portion of that produce, uncharitably exacted for permitting the labourer to consume a part of what he has himself produced." This economic argument formed the foundation of their critique of the existing social order and their proposals for a more just society.

The Ricardian socialists' engagement with Ricardo's system was often selective. They embraced the raw principle that labor determines value but largely ignored the complex qualifications Ricardo had introduced. For example, they did not address his admission that capital intensity affects prices or his detailed analysis of rent as a differential surplus. They also unanimously repudiated the Malthusian theory of population, which was a cornerstone of Ricardo's pessimistic outlook on the long-term prospects for the laboring class.

While the Ricardian socialists' critique of capitalism was fundamentally a moral one, it was built upon a developing economic theory of exploitation. They went beyond the simple assertion of the worker's right to their full produce and attempted to analyze the economic mechanics of how that produce was taken from them. They reframed profit, rent, and interest not merely as unjust deductions, but as the result of the appropriation of "surplus labor"—the labor performed by a worker beyond what is necessary to cover their own subsistence.