Blue Book was a popular 20th-century American magazine with a lengthy 70-year run under various titles from 1905 to 1975. It was a sibling magazine to The Red Book Magazine and The Green Book Magazine. Launched as The Monthly Story Magazine, it was published under that title from May 1905 to August 1906 with a change to The Monthly Story Blue Book Magazine for issues from September 1906 to April 1907. In its early days, Blue Book also carried a supplement on theatre actors called "Stageland". The magazine was aimed at both male and female readers.