This chapter considers the close interrelationship between theatre and cinema during the First World War. As well as looking at key examples of plays which were adapted into films such as The Better ‘Ole (1917) it looks at the relationship between the two modes of popular entertainment, emphasising, for example, how film screenings often incorporated or were incorporated into live performance, and how the two industries shared business practices. The chapter examines the economics and practices of cinema exhibiting, drawing parallels to the regional theatre circuits. It argues for the role of government-endorsed films such as The Battle of the Somme (1916) in establishing the respectability of cinema and demonstrates how from 1917 cinema could shift to being more of a source of entertainment: a shift which threatened the theatre industry. It examines this competition through a focus on the growth of the ‘Super film’ and through attention to the dominance of American films on British screens. The chapter ends with a focus on post-war films. Through discussion the factual war films produced in the 1920s, as well as the fictional dramas, it highlights the ways in which post-war cinema became a means for mediating memory on the war.