New York's Cornell University spends millions of dollars and thousands of staff and volunteer hours to produce more than 1,400 events around the world each year. That's one event every six hours. Is it worth it? Do the 40,000 alumni, parents, and friends who attend feel closer to Cornell after these events? Do they disengage because Cornell didn't deliver the experience they expected? To find out, Cornell is using a new tool--the Net Promoter system (NPS)--to quantify the quality of "customer" relationships. NPS users believe building long-term relationships with customers leads to higher and more sustainable profits. NPS is both a metric (or score) and an approach to conducting business that focuses on the quality of customer relations. Businesses that accept this premise calculate the metric using some form of this question: "On a scale of 0 to 10, how likely are you to recommend X to a colleague or friend?" Answers to a second question, "Why did you answer that way?" initiate a customer feedback loop and help employees identify and fix problems. In this article, the author describes Cornell's experience and the important lessons learned in using the NPS.