Providing great customer service is vital to building a trusting relationship between you and your customers. But how does a help desk ensure that its customers are receiving the help that they need?The CITES Help Desk at the University of Illinois at Urbana-Champaign instituted a quality control program to ensure that our 5000 customer contacts per month receive consistently excellent customer service. In our Quality Assurance for Cases and Knowledgebase (QuACK) program, we review our student consultants' cases and knowledgebase articles for a number of factors including timeliness, clarity of communication, problem solving and successful resolution.Our paper will describe the evolution of our QuACK program, the evaluation criteria that we use, and the improvement we have seen in our communications with our customers.