Beccaria between criminal law and public economics. As Mario Romani wrote in 1966: ‘the most mature and solid part of Beccaria’s work as system builder, that is, his lectures on economia pubblica delivered between 1769 and 1772, and the empirical investigations or consulte stemming from inquiries undertaken in his capacity as a member of government bodies, was for a long time wholly or partly overlooked, or entrusted to unreliable editors, who were ready to print manuscripts the Author himself had not deemed worthy of publication’. This discomfort is no longer justified. The Elementi di economia pubblica will soon be published, while the Atti di Governo have recently appeared in print. We now know the details of Beccaria’s activity in the Supremo Consiglio d’Economia, as Head of the First and then of the Second Department, and as a member of the Consiglio di Governo. We can evaluate his contribution to both theory and practice in the fields of criminal law and economics. The aim of this essay is to assess the consistency between Beccaria’s theoretical writings and his field work, with particular reference to freedom of trade (of grains in particular), free bakery, hunting, forest and mines, the Pizzighettone prison, and the Milan house of correction.