This book constitutes the refereed proceedings of the Second European Conference on Software Architecture, ECSA 2008, held in Paphos, Cyprus, in September/October 2008. The 12 revised full papers presented together with 2 keynote abstracts, 4 experience papers, 7 emerging research papers, and 12 research challenge poster papers were carefully reviewed and selected from 83 submissions. The papers focus on formalisms, technologies, and processes for describing, verifying, validating, transforming, building, and evolving software systems. Topics include architecture modeling, architecture description languages, architectural aspects, architecture analysis, transformation and synthesis, architecture evolution, quality attributes, model-driven engineering, built-in testing and architecture-based support for component-based and service-oriented systems.