The Declaration of Arbroath (Latin: Declaratio Arbroathis; Scots: Declaration o Aiberbrothock; Scottish Gaelic: Tiomnadh Bhruis) is the name usually given to a letter, dated 6 April 1320 at Arbroath, written by Scottish barons and addressed to Pope John XXII. It constituted King Robert I's response to his excommunication for disobeying the pope's demand in 1317 for a truce in the First War of Scottish Independence. The letter asserted the antiquity of the independence of the Kingdom of Scotland, denouncing English attempts to subjugate it.Generally believed to have been written in Arbroath Abbey by Bernard of Kilwinning (or of Linton), then Chancellor of Scotland and Abbot of Arbroath, and sealed by fifty-one magnates and nobles, the letter is the sole survivor of three created at the time. The others were a letter from the King of Scots, Robert I, and a letter from four Scottish bishops which all made similar points. The Declaration was intended to assert Scotland's status as an independent, sovereign state and defend Scotland's right to use military action when unjustly attacked.

Submitted in Latin, the Declaration was little known until the late 17th century and is unmentioned by any of Scotland's major 16th century historians. In the 1680s, the Latin text was printed for the first time and translated into English in the wake of the Glorious Revolution, after which time it was sometimes described as a declaration of independence.