Welcome to the 31st Annual ACM Symposium on User Interface Software and Technology (UIST), held from October 14th to October 17th, 2018, in Berlin, Germany. UIST is the premier forum for presenting innovative research on software and technology for humancomputer interfaces. Sponsored by ACM's special interest groups on computer-human interaction (SIGCHI) and computer graphics (SIGGRAPH), UIST brings together researchers and practitioners from diverse areas, including graphical & web user interfaces, tangible & ubiquitous computing, virtual & augmented reality, multimedia, new input & output devices, fabrication, wearable computing, and computer-supported collaborative work. UIST 2018 received 375 technical paper submissions. After a thorough review process, the program committee accepted 80 papers (21.3%). Each anonymous submission that entered the full review process was first reviewed by three external reviewers, and a meta-review was provided by a program committee member. If, after these four reviews, the submission was deemed to pass a rebuttal threshold, a second member of the program committee provided an additional review. We then asked the authors to submit a rebuttal addressing the reviewers' concerns. The program committee met in person at Microsoft Research in Redmond, WA, USA on June 22nd and 23rd, 2018, to select the papers to invite for the program. After acceptance, authors provided a final revision addressing the committee's comments. Three papers were recognized by the |