Founded in 1912 to protect copyright material. Its categories of membership have changed over the years, and in 1964 its structure added to the League an Authors Guild and a Dramatists Guild. Matters of concern to members in both Guilds (e.g. copyright, freedom of expression) remain the League's province, but matters in which their interests differ (e.g. contract terms, subsidiary rights) are the province of the respective Guilds.