Examining a group of pictures painted in the early-to-mid 1630s, this dissertation sets out to demonstrate that Nicolas Poussin’s turn to the subject of dance helped him transform his style from the sensuous Venetian manner of his early years to the cool, crisp, relief-like approach that would characterize his mature work and form the basis for French Classicism in subsequent decades. Painting dancers allowed Poussin to work through the problem of arresting motion, to explore the affective potential of the body represented, and to discover a measured, geometric compositional method capable of containing and harnessing that potential. The resulting pictures, painted in Rome, were warmly received in Paris by a group of early collectors that included dancers, patrons, amateurs, and theorists of another modern French art: the ballet de cour. Ballet’s cultivation of a fiercely controlled physicality, its wild Dionysian characters and learned Apollonian conceits, above all, its insistence on a hidden geometric order underlying the chaos of embodied experience primed early French observers of Poussin’s dancing pictures to recognize something of themselves in his new approach. Though Poussin did not set out to define French Classicism, and though his brief service as premier peintre to Louis XIII demonstrates how ill-suited he was to the role of official artist, the fact that his dancing pictures shared so much—on the level of patronage, iconography, even, perhaps, theoretical underpinnings—with the ballet de cour may help explain why these works (and, indeed, Poussin himself) were so eagerly appropriated by France in the Classical Age.