Mary Macarthur was born in Glasgow in 1880. Her family were Conservatives and at first she shared the same political beliefs. In 1901 she attended a meeting to discuss the establishment of a branch of the Shop Assistants’ Union, which caused her to rethink her politics. The meeting inspired Mary to become an advocate of trade unionism and a member of the Labour Party.
Mary Macarthur is perhaps best known for founding the National Federation of Women Workers (NFWW) in 1906.