This chapter is devoted to the study of the Institutio oratoria as a complex space in which Quintilian, in addition to developing an education manual, a rhetorical treatise, and an essay on the orator’s moral duties and obligations, also includes theoretical reflections on literary criticism as well as analysis and assessments of specific literary works. In this sense, this chapter studies Quintilian as a literary critic. From a general and theoretical point of view, it reviews the relations established within the framework of the Institutio oratoria between literary criticism and poetarum enarratio, or exegesis of poetic texts, which should be practised by grammar students before continuing to the study of rhetoric. This review forces us to reconsider the question of the interdependence that exists between grammar and rhetoric as classical sciences of discourse. From an applicative and practical perspective, the chapter stresses the importance of Book 10 for a better knowledge of the literary critical analyses and evaluations that Quintilian makes of the most important works and authors of Greek and Roman literature, always in relation to its usefulness for the orator’s training through the exercise of reading and on the basis of the principle of imitation of literary models, which not only include poetic texts, but also historical, philosophical, and rhetorical texts. Finally, the chapter reviews the theory of Attic, Asianic, and Rhodian styles in Quintilian’s thinking and his defence of the one which, even defined by hybridization, best adapts itself to the pragmatic-communicative requirements of the rhetorical fact.