The rise of prose in Greece has been linked to broader cultural and intellectual developments under way in the classical period. Prose has also been characterized as challenging poetry's traditional status as the privileged expression of the culture. Yet throughout the classical period and beyond, poetry was still regularly invoked as the yardstick by which innovation was measured. This paper investigates how poetry figures in the earliest accounts of prose style. Focusing on Isocrates, Alcidamas, and Aristotle, it argues that although each author distinguishes between the styles of prose and poetry, none is able to sustain the distinction consistently. The criteria for what constitutes an acceptable level of poeticality in prose were unstable. The diverse conceptions of poetic style were tied to intellectual polemics and professional rivalries of the early- to mid-fourth century bce and reflect competing aims and ideals for rhetorical performance in prose.