This article argues that the rejection of Sean O’Casey’s The Silver Tassie by Yeats has had consequences for how we think about O’Casey’s drama in general because The Tassie is now regarded as a break in O’Casey’s development. In the first instance this leads to the idea of a Dublin Trilogy rather than a Dublin Quartet. The latter sequence makes much more sense since it is unified by setting, continuous developments in the use of theatrical space and form, theme, and politics. By incorporating The Tassie into O’Casey’s early writing we are enabled to consider again how his work as a whole functions in formal, thematic and political terms.