Process mining builds on two pillars: (a) process modeling and analysis (as de- scribed in Chap. 2) and (b) data mining. This chapter introduces some basic data mining approaches and structures the field. The motivation for doing so is twofold. On the one hand, some process mining techniques build on classical data mining techniques, e.g., discovery and enhancement approaches focusing on data and re- sources. On the other hand, ideas originating from the data mining field will be used for the evaluation of process mining results. For example, one can adopt various data mining approaches to measure the quality of the discovered or enhanced process models. Existing data mining techniques are of little use for control-flow discovery, conformance checking, and other process mining tasks. Nevertheless, a basic under- standing of data mining is most helpful for fully understanding the process mining techniques presented in subsequent chapters.