This thesis examines the presence and use of colour in the plays of Sean O’Casey and argues that while a portion of colour in the drama is aesthetic, another portion is intentionally utilized as a means to provide additional contextual commentary, be it cultural, religious, political, or artistic in nature. This practice stems, I argue, in part because of O’Casey’s tendency towards an appreciation for beautiful things stemming from his artistic leanings. I also argue that the politics of his youth: associations with the Irish Citizen Army and the Labour Movement, his family’s poverty due to the early passing of his father Michael, his relationship with religion, and his desire to open the arts to the masses influenced how and why he wrote. I use as a support to these ideas Michael Pierse’s recent publication on Irish working-class writing history and the colour theories of Sabine Doran and Ulf Klaren and Karin Fridell Anter to analyse the texts of the plays as well as analysing productions of eight O’Casey plays. I come to the conclusion that O’Casey utilized colour as a means of enhancing the reality perceived within his plays to provide context on the various historical, political, and social movements addressed.