Piero Sraffa FBA (5 August 1898 – 3 September 1983) was an influential Italian political economist who served as lecturer of economics at the University of Cambridge. His book Production of Commodities by Means of Commodities is taken as founding the neo-Ricardian school of economics.

Sraffa was born in Turin, Kingdom of Italy, to Angelo Sraffa (1865–1937) and Irma Sraffa (née Tivoli) (1873–1949), a wealthy Italian Jewish couple. His father was a professor in commercial law and later dean at the Bocconi University in Milan. Despite being raised as a practising Jew, Sraffa later became an agnostic.

Due to his father's activity, the young Piero followed him during his academic wanderings (University of Parma, University of Milan and University of Turin), where he met Antonio Gramsci (leader of Communist Party of Italy). They became close friends, partly due to their shared political views. Sraffa was also in contact with Filippo Turati, perhaps the most important leader of the Italian Socialist Party, whom he allegedly met and frequently visited in Rapallo, where his family had a holiday villa. At the age of 18, in the spring of 1917, he began military service as an officer of the Military Engineer Corps, under the command of the First Army as rear-guard. From the end of World War I (November 1918) until March 1920 he was a member of the Royal Commission of Inquiry into the violations of the right of the people committed by the enemy. The military period corresponded to the "university" one; some anecdotes tell of exams done effortlessly wearing the officer uniform. He graduated in November 1920 with a thesis on inflation in Italy during the period of the Great War. His tutor was Luigi Einaudi, one of the most important Italian economists and later a president of the Italian Republic.

From 1921 to 1922, he studied at the London School of Economics. During this period, at Cambridge, he met twice John Maynard Keynes, who invited him to a collaboration. This request led Sraffa to write two articles about the Italian banking system published in 1922, the first (The Bank Crisis in Italy) in The Economic Journal (edited by Keynes) and the second (The current situation of Italian banks) in the supplement of the newspaper Manchester Guardian (now The Guardian). Keynes also entrusted Sraffa with the Italian edition of his A Tract on Monetary Reform. The meeting with Keynes was undoubtedly a fundamental turning point in Sraffa's career.

In 1922 Sraffa was appointed director of the provincial labour department in Milan, where he frequented socialist circles. In this period he made friends with Carlo Rosselli and Raffaele Mattioli, both assistants of Luigi Einaudi at the time.

The march on Rome, with the consequent seizure of power by Mussolini, was an event destined to affect deeply his future. His father Angelo was the target of aggression by a fascist squad and received two very threatening telegrams by Mussolini himself who required a public retraction by Piero on the content of the second article published in the Manchester Guardian. Piero did not write a retraction. In May 1924 his friend Antonio Gramsci, who found himself stuck firstly in Moscow and then in Vienna due to the advent to power of fascism, returned to Rome on his election to Parliament. From now on the relations between the two intellectuals intensified. On 26 November 1926 Italian Parliament approved the law "defence of the state", thus giving rise to the totalitarian state. On 8 November 1926, Antonio Gramsci was arrested. During Gramsci's incarceration, Sraffa supplied books and the material, literally pens and paper, with which Gramsci would write his Prison Notebooks.

In 1925, Sraffa wrote about returns to scale and perfect competition. In the 1926 article, "The Laws of Returns under Competitive Conditions", published in The Economic Journal, Sraffa resumes and develops his work of 1925 to show the inconsistency of the Marshallian theory of partial equilibrium, according to which, in competition for each good:

Sraffa notes that the law of decreasing returns and that of increasing returns have different origins and areas of application (and therefore cannot explain the shape of the same supply curve): the law of diminishing returns was originally applied to the entire economy and resulted from the scarcity of the agricultural land as a mean of production (the rent theory of David Ricardo); while the law of increasing returns applied to the individual firm and resulted from the benefits of division of labour. The first one allowed for the study of the laws of distribution, and the second those of production.