Martin Luther King Day is a United States holiday honoring the Reverend Martin Luther King Jr, observed on the third Monday of January each year, around the time of King's birthday, January 15.

At the White House Rose Garden on November 2, 1983, US President Ronald Reagan signed a bill creating a federal holiday to honor King. It was observed for the first time on January 20, 1986.

On January 18, 1993, for the first time, Martin Luther King Day was officially observed in all 50 United States states. The day is marked by demonstrations for peace, social justice and racial and class equality, as well as a national "day on" of volunteer community service.

Although the day is a federal holiday and a state holiday in all states, it is usually not observed by private companies.