The Italian Republican Party is a political party in Italy established in 1895, which makes it the oldest political party still active in the country. The PRI identifies with 19th-century classical radicalism, as well as Mazzinianism, and its modern incarnation is associated with liberalism, social liberalism, and centrism. The PRI has old roots and a long history that began with a left-wing position, being the heir of the Historical Far Left and claiming descent from the political thought of Giuseppe Mazzini and Giuseppe Garibaldi. With the rise of the Italian Communist Party and the Italian Socialist Party (PSI) to its left, it was associated with centre-left politics. The early PRI was also known for its anti-clerical, anti-monarchist, republican, and later anti-fascist stances. While maintaining those traits, during the second half of the 20th century the party moved towards the centre on the left–right political spectrum, becoming increasingly economically liberal.

Giuseppe Mazzini was an Italian politician, journalist, and activist for the unification of Italy (Risorgimento) and spearhead of the Italian revolutionary movement. His efforts helped bring about the independent and unified Italy in place of the several separate states, many dominated by foreign powers, that existed until the 19th century. An Italian nationalist in the historical radical tradition and a proponent of a republicanism of social-democratic inspiration, Mazzini helped define the modern European movement for popular democracy in a republican state.