Pontormo's frescoes in San Lorenzo were the most important cycle of the sixteenth century after Michelangelo's Sistine frescoes. They had an enormous impact on artists until their destruction in the eighteenth century, and their interpretation has also had a significant bearing not only on the reception of this artist, but also of late Renaissance art in Florence. Based on archival and historical research, this book determines a new date for the inception of the fresco cycle and reconstructs the day-by-day activity in the church that had an impact on Pontormo's project. It reveals Pontormo's painstaking working method. The new reconstruction corrects the visual order of the frescoed scenes, and conclusively demonstrates the orthodoxy of the choir's iconography. It sets them into the artistic and architectural context of the church of San Lorenzo, relating them to works of art by Fra Bartolomeo and Michelangelo, as well as to complex liturgical and religious functions. This study establishes the intentions of the Medici and the canons of the church in having Pontormo paint the specific space in the church where he painted, and the specific subjects that were included. Finally, it reveals the unsuspected impact Pontormo's paintings had on other works of art.