This chapter introduces Raising as an operation which is used as a pre-processing step for Data Mining. In the Web Marketing Project, people’s demographic and interest information has been collected from the Web. Rules have been derived using this information as input for data mining. The Raising step takes advantage of an interest ontology to advance data mining and to improve rule quality. The definition and implementation of Raising are presented in this chapter. Furthermore, the effects caused by Raising are analyzed in detail, showing an improvement of the support and confidence values of useful association rules for marketing purposes.