The1stEuropeanWorkshoponSoftwareArchitecture(EWSA2004)washeldin St Andrews, Scotland on 21–22 May 2004. The workshop provided an inter- tional forum for researchers and practitioners from academia and industry to discuss a wide range of topics in the area of software architecture and to jointly formulate an agenda for future research. We were pleased to continue this forum in EWSA 2005. The importance of software architecture as a fundamental area of software engineeringcontinues togrow.Inaddition todescribingtheunderlyingstructure of software systems, architectures are now being used to model and understand dynamicbehavior.Newareasofstudy,whichhavetheirrootsincontrolsystems, arebeginningtoemerge.The?eldofautonomicsrequiresanunderlyingsoftware architecture to describe the executing computation as does any control system that involves system evolution. The range of papers in EWSA 2005 re?ected both the traditional and new applications of software architecture techniques. EWSA 2005 distinguished between three types of papers: research papers (which describe authors’ novel research work), a case study (which describes experiencesrelatedtosoftwarearchitectures)andpositionpapers(whichpresent concise arguments about a topic of software architecture research or practice). TheProgrammeCommitteeselected18papers(12researchpapers,4position papers, 1 case study, and 1 unrefereed invited paper) out of 41 submissions from 20 countries (Australia, Belgium, Brazil, Chile, China, Czech Republic, Finland, France, Germany, India, Italy, Ireland, Korea, Netherlands, Pakistan, Portugal, Spain, Switzerland, UK, USA). All submissions were reviewed by at least three members of the Programme Committee. Papers were selected based on originality, quality, soundness and relevance to theworkshop. Credit for the quality of the proceedings goes to all authors of papers.