In April 2015, a subgroup of the University Libraries' Discovery Group began its two phase usability testing, conducting the first phase on WorldCat Local. In July of 2015, the Libraries transitioned from WorldCat Local to WorldCat Discovery. In October-November 2015, the subgroup conducted the second phase of usability testing on WorldCat Discovery. The subgroup presented its first round results at the Libraries Research and Innovative Practice Forum in June 2015, and the overall results at the following year’s forum in June 2016. This report is the formal write-up for the project.