When in 1986 Yves Kodratoff started the European Working Session on Learning at Orsay, France, it could not be foreseen that the conference would grow year by year and become the premier European conference of the field, attracting submissions from all over the world. The first European Conference on Principles of Data Mining and Knowledge Discovery was organized by Henryk Jan Komorowski and Jan Zytkow in 1997 in Trondheim, Norway. Since 2001 the two conferences have been collocated, offering participants from both areas the opportunity to listen to each other’s talks. This year, the integration has moved even further. Instead of first splitting the field according to ECML or PKDD topics, we flattened the structure of the field to a single set of topics. For each of the topics, experts were invited to the Program Committee. Submitted papers were gathered into one collection and characterized according to their topics. The reviewers were then asked to bid on all papers, regardless of the conference. This allowed us to allocate papers more precisely.

This book constitutes the refereed proceedings of the joint conference on Machine Learning and Knowledge Discovery in Databases: ECML PKDD 2008, held in Antwerp, Belgium, in September 2008.

The 100 papers presented in two volumes, together with 5 invited talks, were carefully reviewed and selected from 521 submissions. In addition to the regular papers the volume contains 14 abstracts of papers appearing in full version in the Machine Learning Journal and the Knowledge Discovery and Databases Journal of Springer.

The conference intends to provide an international forum for the discussion of the latest high quality research results in all areas related to machine learning and knowledge discovery in databases. The topics addressed are application of machine learning and data mining methods to real-world problems, particularly exploratory research that describes novel learning and mining tasks and applications requiring non-standard techniques.