A shift occurred over the course of the 15th century in the design (but not function) of altarpieces. The structure of altarpieces changed as did the way that these were evaluated by contemporaries. ‘The art of the altarpiece’ charts this change from material to artistic values and asks why it happened when it did. The altarpiece tradition continued into the next century and beyond in Italy, France, Spain, and the Catholic areas of Northern Europe. But the tradition came to an abrupt end in the North with the Reformation. In Catholic areas, however, the altarpiece tradition continued.