Foreword In many cases competitiveness of modern products is defined by the degree of customization, i.e. the ability of a manufacturer to adapt a product according to customer requirements. Knowledge based configuration methods support the composition of complex systems from a set of adjustable components. However, there are two important prerequisites for a successful application of knowledge-based configuration in practice: (a) expressive knowledge representation languages, which are able to capture the complexity of various models of configurable products and (b) powerful reasoning methods which are capable of providing services such as solution search, optimization, diagnosis, etc. The Configuration Workshop aims to bring together industry representatives and researchers from various areas of AI to identify important configuration scenarios found in practice, exchange ideas and experiences and present original methods developed to solve configuration problems. The workshop continues the series of successful Configuration Workshops started at the AAAI’96 Fall Symposium and continued on IJCAI, AAAI, and ECAI since 1999. During this time the focus of the events broadened from configuration approaches applied to traditional products such as cars, digital cameras, PC, telecommunication switches or railway interlock systems to configuration of software and services available on the Web. In parallel, research in the field of constraint programming, description logic, non-monotonic reasoning, fundamentals of configuration modeling and so forth pushed the limits of configuration systems even further. The papers selected this year for presentation on the Configuration Workshop continue a recent trend in the research community and focus on modeling and solving of configuration problems. Wolfgang Mayer and Patrick Albert July 2012 Wolfgang Mayer and Patrick Albert, Editors. Proceedings of the Workshop on Configuration at ECAI 2012 (ConfWS’12), August 27, 2012, Montpellier, France. Workshop Organization Program Co-Chairs Wolfgang Mayer University of South Australia, Adelaide, Australia Patrick Albert IBM, France Program Committee Tomas Axling Tacton Systems AB, Sweden Claire Bagley Oracle Corporation, USA Conrad Drescher University of Oxford, UK Alexander Felfernig Technische Universität Graz/Configworks, Austria Gerhard Friedrich AAU Klagenfurt, Austria Albert Haag SAP AG, Germany Alois Haselboeck Siemens AG, Austria Lothar Hotz Universität Hamburg, Germany Klas Orsvarn Tacton System AB, Sweden Markus Stumptner University of South Australia, Australia Barry O’Sullivan Cork Constraint Computation Centre, Ireland Juha Tiihonen Aalto University, Finland Wolfgang Mayer and Patrick Albert, Editors. Proceedings of the Workshop on Configuration at ECAI 2012 (ConfWS’12), August 27, 2012, Montpellier, France.