This work compiles the history of the Donegal pilgrimage as presented in historical texts, guidebooks, popular writing, devotional treatises, and newspaper and journal accounts. This material - with its cultural, political, as well as religious associations - provides background for these poets' Lough Derg poems, which relate their own pilgrimage experiences. The book proceeds to examine Devlin's Lough Derg, Kavanagh's Lough Derg, and Heaney's Station Island. The question is why do three mid-career Irish poets choose to write ambitious and problematic poems about the Lough Derg experience? The answer is found in the competing proprietary claims of what began as an early medieval imagining of Purgatory and becomes in the twentieth century a template for artistic and spiritual conversion.