Prayers and Portraits: Unfolding the Netherlandish Diptych is the scholarly catalogue accompanying an exhibition organized by its authors for the National Gallery of Art in Washington and the Koninklijk Museum voor Schone Kunsten in Antwerp, in association with the Harvard University Art Museums. Complementing the volume is a second book, Essays in Context: Unfolding the Netherlandish Diptych (John Oliver Hand and Ron Spronk, eds., Cambridge, MA: Harvard University Press, 2006), which collects writings by thirteen specialists from the field of Netherlandish art history. The catalogue focuses primarily on material, technical, and qualitative issues contextualized by format and use, while its counterpart offers “interdisciplinary” perspectives, meaning perspectives from “different fields of art history.” The books thus have distinct objectives. In approaching the catalogue as an autonomous work, I found the technical information fascinating, and the illustrations evocative and unparalleled in quality for diptych studies. The positive features of the volume are tempered, however, by reductive discussions of non-technical issues that fail to do justice to this important Renaissance art form. The catalogue opens with two brief essays: “The Diptych Format in Netherlandish Painting” and “Material and Technical Aspects of the Netherlandish Diptych.” The former covers more territory than its narrow title...