18th International Conference on Calorimetry in High Energy Physics (CALOR 2018)James E. BrauUniversity of Oregonjimbrau@uoregon.edu1. PrefaceThe 18th International Conference on Calorimetry in High Energy Physics - CALOR 2018 - was held in Eugene, Oregon, USA from 21-25 May, 2018, on the campus of the University of Oregon. It was hosted by the University of Oregon Center for High Energy Physics.The CALOR series of conferences was first held at Fermilab in 1990. Major focuses include operating calorimeter systems and development of future calorimeters within the High Energy Physics community. In addition, related calorimetric applications in other fields, such as Astrophysics and Medical Imaging, have been included. This year the conference attracted fifty-nine oral presentations and two posters, and was attended by eighty registrants. This volume contains the written contributions of forty-four of the contributions.The conference opened with welcome remarks by Oregon’s Vice President for Research and Innovation, Professor David Conover, and the Divisional Dean for Natural Sciences, Professor Hal Sadofsky. After these brief remarks, the program began and continued for five days of high-quality presentations on a range of topics of scientific interest.List of International Advisory Committee, Local Organizing Committee, Session Chairs and List of Participants are available in this pdf.