The National Mediation Board (NMB) is an independent agency of the United States government that coordinates labor-management relations within the U.S. railroads and airlines industries.

The board was established by the 1934 amendments to the Railway Labor Act of 1926 and is headed by a three-person panel of Presidential appointees.

NMB programs provide an integrated dispute resolution process to meet the statutory objective of minimizing strikes and other work stoppages in the airline and railroad industries.

The NMB's integrated processes specifically are designed to promote three statutory goals: Under the Railway Labor Act, an airline or railroad union contract does not expire; it remains in force and amendable until a new contract is ratified by the union members or either side exercises "self-help," which could be a strike by employees or a lockout by management.

The Board is composed of three members, nominated by the President of the United States, with the advice and consent of the Senate, for terms of three years.