The Crucifixion of Saint Andrew (1606–7) marks a crucial turning point in the life and artistic development of Michelangelo Merisi da Caravaggio (1571–1610). One of seven Caravaggio paintings in US collections, and the only altarpiece, it exemplifies the influential tenebristic style the artist developed during his rise to fame in Rome, while signaling the introduction of an even grittier realism in his work. This is the first book-length publication to consider this understudied masterwork in its complex historical and geographic contexts, and to incorporate the findings of a recent conservation study in its assessment of the work.