This dissertation presents Gaelic perceptions and expressions of leadership in Ireland, c.1400 – c.1600, as found in Gaelic literary sources, with special emphasis on the work of the professional court poets. It is a literary study which, while set against the historical background, is concerned with questions of lexis, rhetoric, stylistic forms and techniques, and cultural systems. Because of the particular interest of the issue of nationalism in later sixteenth-century Ireland, the work has been divided into two parts, the chronological split being placed about 1560: this makes a comparison possible between the themes present in late sixteenth-century literature and those found in earlier texts. Because so much of the poetry was commissioned by the chiefs themselves, of interest is also the question of poetic sincerity as opposed to mere flattery. This dissertation provides an examination of the careers of twenty-nine fifteenth- and sixteenth-century leaders, and opinions about them as expressed by contemporary and near-contemporary Gaelic commentators. These leaders, established in the various provinces of Ireland, vary in their ethnicities as well as in their political inclinations. The evidence gathered (which includes chronicles and well over two hundred poems) is explored in search of trends and themes, and a pattern is proposed – tentatively, for so much material still needs to be researched – for ideal political leadership as perceived and expressed by the native literary elite.