Late Medieval and Renaissance art was surprisingly pushy; its architecture demanded that people move through it in prescribed patterns, its sculptures played elaborate games alternating between concealment and revelation, while its paintings charged viewers with imaginatively moving through them. Viewers wanted to interact with artwork in emotional and/or performative ways. This inventive and personal interface between viewers and artists sometimes conflicted with the Church's prescribed devotional models, and in some cases it complemented them. Artists and patrons responded to the desire for both spontaneous and sanctioned interactions by creating original ways to amplify devotional experiences. The authors included here study the provocation and the reactions associated with medieval and Renaissance art and architecture. These essays trace the impetus towards interactivity from the points of view of their creators and those who used them. Contributors include: Mickey Abel, Alfred Acres, Kathleen Ashley, Viola Belghaus, Sarah Blick, Erika Boeckeler, Robert L.A. Clark, Lloyd DeWitt, Michelle Erhardt, Megan H. Foster-Campbell, Juan Luis Gonzalez Garcia, Laura D. Gelfand, Elina Gertsman, Walter S. Gibson, Margaret Goehring, Lex Hermans, Fredrika Jacobs, Annette LeZotte, Jane C. Long, Henry Luttikhuizen, Elizabeth Monroe, Scott B. Montgomery, Amy M. Morris, Vibeke Olson, Katherine Poole, Alexa Sand, Donna L. Sadler, Pamela Sheingorn, Suzanne Karr Schmidt, Anne Rudloff Stanton, Janet Snyder, Rita Tekippe, Mark Trowbridge, Mark S. Tucker, Kristen Van Ausdall, Susan Ward.