This article explores the Jewish working-class poet John Rodker’s writing for and about the stage as an overlooked, alternative theorisation of modernist theatre and its artistic and institutional function. It retraces the origins of his 1914 theatre manifesto, published in the magazine The Egoist, to his earlier theatre criticism to show that Rodker initially took an interest in the stage, above all, as a tool for the political engagement and artistic education of the masses. I discuss three theatre critiques, published in The Freewoman and Poetry and Drama between 1912–1913, in which Rodker considers three different types of contemporary theatre with a view to their effectiveness in engaging popular audiences in contemporary social and aesthetic debates. While he criticises the commercial West End theatre and regional repertory companies for their failure to promote social and cultural reform, he lauds the local Yiddish theatre in London’s East End as a true community theatre and the home of a revolutionary modern drama. By highlighting the role played by the popular Yiddish theatre in Whitechapel in shaping Rodker’s ideas for an institutionally and artistically reformed modernist stage, this article aims to restore a forgotten piece of working-class history to our critical conception of modernist drama.