A Deputy Chief of Mission (DCM, in Europe a term Deputy Head of Mission is used instead of), is the number-two diplomat assigned to an embassy or other diplomatic mission. He or she is usually considered the second-in-command or top lieutenant to the Head of Mission (usually an ambassador). DCMs serve as chargé d'affaires (that is, as Acting Chief of Mission) when the titular Head of Mission is outside of the host country or when the post is vacant.
DCMs typically serve as a key advisor to the Chief of Mission as well as a chief of staff, responsible for the day-to-day management of the post. The DCM will oversee the heads of sections (Political, Economic, Public Affairs, Management, Consular) at the Embassy, such as the DCMs also serve as de facto ombudsmen, responding to employee concerns and quality of life issues. Most career Ambassadors have served as a DCM prior to their first assignment as Chief of Mission. In embassies where the Ambassador/ Chief of Mission is typically a political appointee, the Deputy Chief of Mission will nearly always be a career diplomat.