Letter of credence

A letter of credence (French: Lettre de créance) is a formal diplomatic letter that designates a diplomat as ambassador to another sovereign state. Commonly known as diplomatic credentials, the letter is addressed from one head of state to another, asking them to give credence (French: créance) to the ambassador's claim of speaking for their country. The letter is presented personally by the ambassador-designate to the receiving head of state in a formal ceremony, marking the beginning of the ambassadorship.

Letters of credence are traditionally written in French, the lingua franca of diplomacy. However, they may also be written in the official language of the sending state.