Pressing Matters is a publication from the Department of Architecture at the University of Pennsylvania School of Design, and is designed by the renowned New-York based studio WSDIA wsdia.com]. It has been published annually since 2013. Each volume of Pressing Matters features the programs and studios offered during each academic semesters for the year, as well as student and faculty news, student work, and coordinator's mission statements. Pressing Matters 4 also specifically zooms in on our 125 year celebration, lectures from the 2014-2015 academic year and a special article on the "YES pavilion," a wonderful smart-structure designed by our first year students under the guidance of Professors Danielle Willems and Ezio Blasetti, and constructed by a collaboration of 500, 600, and 700 students under the guidance of Professor Mohamad Al Khayer. We are also environmentally conscious; as always the book was printed using recycled paper and non-toxic inks and is available online as an E-book.