Discussing How To Read Medieval Art within the context of a review for fellow specialists runs the risk of misapprehending a book obviously written for our period, broadly, and for a broad audience. It is clearly not meant for us. Most of the material we know, since it all comes from a beloved and familiar collection at the Metropolitan Museum, which comprises among its venues the finest assemblage of medieval art in the US. Most of the explanations for the art are familiar to this review's audience, which likely at some point also teaches this art to undergraduates with little direct experience of it beforehand. It takes a little effort, then, to read How To Read on its own terms, and not as a document itself, reflecting museum pedagogy and its methodological assumptions about understandings and values of museum holdings. The series (the other five volumes include topics like Chinese ceramics and Islamic carpets, as well as comparable surveys such as Oceanic art) selects solely from the Met's collection. It is a world within a world, a whole set of cultures called Medieval constituted by one museum, which houses and shows so many more than this set called Medieval. The book, and the series to which it belongs, are a testimony to the range of the colossus on Fifth Avenue.
The extraordinarily vivid photographs, which are numerous and wonderful, encourage this kind of close-reading analysis, if your training and disposition incline you that way. The introduction begins with the statement that "The art of the Middle Ages is an art of storytelling" (9). And this position marks a primary purpose and organizing principle of the book; literacy in the stories of the Middle Ages is indeed an excellent starting point. And yet the facing page shows a detail of the head of the Virgin (twelfth-century Auvergne, entry 22 here) with beautiful sympathy, age marks intact, and textures, wood and paint traces brought richly to the fore; the face, however, is turned at a slight angle away from the text, and her strongly discrete qualities, underlined by the unreadable eyes and the still, closed mouth, indicate that the story is told elsewhere. Photographer and designer are colluding with authorial and institutional positions.
In this vein--and I would make no claim that this vein is correct or necessary, only a professional failing in a member probably of the not-audience--the cover performs another visual authorial stance. Here, the central panel of the Merode Altarpiece (entry 29 here) illustrates the title, which is shown in a banner aligned with the ceiling of the room of the Annunciation in this Flemish Nazareth. The scene is naturally well-known: the Virgin Mary reads from a cloth-covered book, as Gabriel arrives with the moment of conception; between them is a table with a book bag, scroll and another book, as well as a vase and candlestick. The candle smokes, and the book's pages flutter; the inrush of the Holy Spirit is nearly upon Mary, still caught up in her reading. On the one hand, it is difficult to escape an intended connection between How To Read above the scene with instruction on how to read being given by Gabriel to Mary; and on the other, not to take Gabriel's position as the museum docent's delivering the word on "Medieval Art" to a passive recipient. The absence of the author's name on the cover (her surname is on the spine of the book) suggests a similarly elevated delivery of "How To" to a careful 'reader' of text and image, which ought to be all medieval art historians after all.  Now, this 'reading' might be an idle exercise, or it might be the natural outcome of the process the author admirably espouses, that is, "...taking time to look at works of art and to know the story that is being depicted." Her premise for the book's presentation and organization is compelling, "...not just identifying a particular scene, but using the evolution of that scene to illustrate more subtle and intellectually rich historical, theological, and sociological concepts." 
While the art might be resistant--see again the stumm, aloof Virgin opposite the introduction--or it might be manipulated to express divine authority in pedagogy--the Archangel as patron of docents, on the cover--the text itself does not insist strongly or exclusively on certain readings over others. It does not reveal much diversity of method or of explanation on the surface, but it is also generous and thoughtful in its 'readings.' If one strays into unpersuasively close readings of text and image in this book, it is partly because the author opens up these possibilities to reach what could be the rich concepts the author signals is waiting for careful lookers (and maybe readers too). Those lookers are going to be museum visitors, it would seem likely to this reader, because the book doesn't lend itself, to my thinking, to classroom use away from New York. And in this way, the book might have stepped back and thought about museum access and presentation, and their impact on our understandings of Medieval. The book's world is clearly submerged within that bigger world of the series and the museum itself, where the bigger world is not visible any longer. As these books reveal, just the same, it is a seductive, beautiful world, worth guarding, as the fourteenth-century ivory (entry 35 here) of a (metaphorical) attack on a city shown in detail on the back cover makes clear. Despite recent sieges, the Met keeps its world of marvels intact.
-------- Notes: 1. Six volumes are in the Met's "How To Read" series to date, and none include the author on the front cover, although the first three volumes state the institutional origin of the book below the volume's title. 2. http://www.metmuseum.org/blogs/now-at-the-met/2016/how-to-read-medieval-art [accessed 19 May 2017].