The thesis focuses on Plato’s treatment of poetry in the Ion, Gorgias and Republic X. Although these discussions provide three quite different accounts of poets and their activity and have thus commonly not been associated, a similar objective may be detected in them: they all aim to disqualify poets, presenting them as incompetent in what they do or also (in the Gorgias and Republic X) as morally harmful. My aim is first to show how the three discussions differ from Plato’s other major discussions of poetry in Republic II-III and Laws II and VII: while the former provide (disqualifying) answers to the descriptive questions of whether poets have relevant knowledge and how they morally affect their public, the latter are concerned with the prescriptive questions of what poets should do in their envisaged role as political instruments (Chapter I). In the close study of the three discussions, my aim is to identify, critically examine and compare the ‘disqualifying’ strategies employed in them: I consider, on the one hand, how they substantiate the charges of poets’ incompetence or moral harmfulness and on the other hand, how they counter and account for the widely shared appreciation of Homer and other poets (Chapters II-V). Before discussing Republic X, however, I consider separately the notion of poets’ μίμησις (representation/ imitation), which in Republic X has a prominent role, but at the same time appears difficult to understand in itself as well as seemingly inconsistent with Plato’s other arguments about poets’ μίμησις, in particular in Republic III. Rejecting the widely accepted assumption of ‘narrower’ and ‘wider’ meanings of the term μίμησις respectively in Books III and X of the Republic, I analyse the notion of μίμησις in itself, and, following this I distinguish between three kinds of poets’ μίμησις and define in what elements they differ (Chapter IV). In the final overview of the three discussions, I reconsider how successful are their disqualifying depictions of poets.