Using a sociolinguistic and post-colonial approach, I analyze Irish dramas that speak about language and its connection to national identity. In order to provide a systematic and wide-ranging study, I have selected plays written at approximately fifty-year intervals and performed before Irish audiences contemporary to their writing. The writers selected represent various aspects of Irish society--religiously, economically, and geographically--and arguably may be considered the outstanding theatrical Irish voices of their respective generations. Examining works by Alicia LeFanu, Dion Boucicault, W.B. Yeats, and Brian Friel, I argue that the way each of these playwrights deals with language and identity demonstrates successful resistance to the destruction of Irish identity by the dominant language power. The work of J. A. Laponce and Ronald Wardhaugh informs my language dominance theory. Briefly, when one language pushes aside another language, the cultural identity begins to shift. The literature of a nation provides evidence of the shifting perception. Drama, because of its performance qualities, provides the most complex and complete literary evidence. The effect of the performed text upon the audience validates a cultural reception beyond what would be possible with isolated readers. Following a theoretical introduction, I analyze the plays in chronological order. Alicia LeFanu's The Sons of Erin; or, Modern Sentiment (1812) gently pleads for equal treatment in a united Britain. Dion Boucicault's three Irish plays, especially The Colleen Bawn (1860) but also Arrah-na-Pogue (1864) and The Shaughraun (1875), satirically conceal rebellious nationalist tendencies under the cloak of melodrama. W. B. Yeats's The Countess Cathleen (1899) reveals his romantic hope for healing the national identity through the powers of language. However, The Only Jealousy of Emer (1919) and The Death of Cuchulain (1939) reveal an increasing distrust of language to mythically heal Ireland. Brian Friel's Translations (1980), supported by The Communication Cord (1982) and Making History (1988), demonstrates a post-colonial move to manipulate history in order to tell the Irish side of a British story, constructing in the process an Irish identity that is postnational.