Historians of rhetoric continue to debate the relative degree of transmission and implementation of the progymnasmata during the Middle Ages. This essay intervenes in this debate by analyzing Matthew of Vendôme's Ars versificatoria ( Art of the Versemaker), showing that the treatise emphasizes the construction of probable assertions within a system of rhetorically-informed poetic composition. While past scholarship has shown Matthew's indebtedness to Ciceronian and Horatian rhetoric and poetics, this essay argues that progymnasmata exercises focused on probability and verisimilitude may have also influenced Matthew, suggesting the continued influence of the exercises within rhetorical and grammatical education during the 12th century.