The book "Machine Learning: ECML 2007" documents the results of the seventh joint conference of the European Conference on Machine Learning (ECML) and the European Conference on Principles and Practice of Knowledge Discovery in Databases (PKDD), which took place from September 17 to 21, 2007, in Warsaw. Since its first event in 1986, this conference has developed into one of the most significant international platforms for the exchange of research results in the fields of machine learning and data analysis. The publication provides a comprehensive overview of the latest developments and trends in these dynamic research areas. The contributions come from leading scientists and cover a wide range of topics that are important for the advancement of algorithms and methods in machine learning. The careful selection of contributions and the hierarchical review by a renowned program committee ensure the high quality of the included works.