This book constitutes the refereed proceedings of the 9th Industrial Conference on Data Mining, ICDM 2009, held in Leipzig, Germany in July 2009. The 32 revised full papers presented were carefully reviewed and selected from 130 submissions. The papers are organized in topical sections on data mining in medicine and agriculture, data mining in marketing, finance and telecommunication, data mining in process control, industry and society, data mining on multimedia data and theoretical aspects of data mining.