Receiver Operating Characteristics (ROC) graph is a popular way of assessing the performance of classification rules. However, as such graphs are based on class conditional probabilities, they are inappropriate to evaluate the quality of association rules. This follows from the fact that there is no class in association rule mining, and the consequent part of two different association rules might not have any correlation at all. This chapter presents an extension of ROC graphs, named QROC (for Quality ROC), which can be used in association rule context. Furthermore, QROC can be used to help analysts to evaluate the relative interestingness among different association rules in different cost scenarios.