The Tarnovo Constitution (Търновска конституция) was the first constitution of Bulgaria. It was adopted on 16 April 1879 (28 April greg.) by the Constituent National Assembly held in Veliko Tarnovo as part of the establishment of the Principality of Bulgaria.
The constitution was bourgeois-liberal in character and defined the functions and competences of the central organs of state authority according to the principle of separation of powers between an executive, a legislative, and a judiciary branch. Ministerial responsibility, immunity of the deputies, and inviolability of private property were also proclaimed. The constitution included a clause that formally established the Bulgarian Orthodox Church as the official religion of the nation.
With corrections in 1893 and 1911, resulting in the strengthening of monarchic power, the Tarnovo Constitution remained in use until 4 December 1947, when it was replaced by the Constitution of the People's Republic of Bulgaria.