Celebrated draughtsman, painter and printmaker, Battista Franco (c. 1510–1561), enjoyed a well-documented career in Rome, Florence, Urbino and his native Venice where he returned for the remaining decade of his life. However, even his well-informed biographer, Giorgio Vasari, was unaware of his trip to Osimo, a small town in the province of Ancona in the Marche. Franco was commissioned by an Osimo confraternity in 1547 to decorate an altarpiece and ciborium for the main altar of the cathedral. Though now divested of its original trappings, the resulting fourteen-panel polyptych, preserved today in the cathedral museum, remains nonetheless an impressive work, but one little-known outside specialist circles. The identification of ten preparatory drawings for it published here together for the first time, allow for a renewed appreciation of the altarpiece and the artistic process behind its creation. In several respects these studies, important additions to Franco’s corpus of autograph drawings, do not bear the typical hallmarks of his graphic style as shown by the variety of names under which they were found from Moncalvo to Agostino Carracci. This new crop of studies adds a new dimension to our understanding of Franco’s ever varied draughtsmanship as it evolved in the latter half of the 1540s. Considered together with the related panels, they present an artist embracing not only the work of Michelangelo but that of Raphael and Polidoro da Caravaggio as well.