Arthur Greenwood was a British politician. A prominent member of the Labour Party from the 1920s until the late 1940s, Greenwood rose to prominence within the party as secretary of its research department from 1920 and served as Parliamentary Secretary to the Ministry of Health in the short-lived Labour government of 1924. In 1940, he was instrumental in resolving that Britain would continue fighting Nazi Germany in World War II.

The first MacDonald ministry of the United Kingdom lasted from January to November 1924. The Labour Party, under Ramsay MacDonald, had failed to win the general election of December 1923, with 191 seats, although the combined Opposition tally exceeded that of the Conservative government, creating a hung parliament. Stanley Baldwin remained in office until January 1924.