As the field of software architecture matures, several trends can be observed. The first is a recognition of the role of software architecture in all phases of software development. Whereas initially software architecture was primarily associated with the architecture design phase, we now see that software architecture is treated explicitly during development, product derivation in software product lines, at run-time, and during system evolution. A second trend is explicitly relating architecture design decisions to the requirements satisfied by these design decisions. Another trend is the increased use of quantitative assessment of software architectures. Finally, we see continued work on dynamic software architectures, with challenges arising from applications involving ubiquitous computing, mobile collaboration, and mobile computing. These trends can be seen in the papers collected in this volume, which represent some of the latest work by researchers and practitioners. The papers were presented at the 3rd Working IEEE/IFIP Conference on Software Architecture (WICSA3), which was held in conjunction with the 17th World Computer Congress, sponsored by the International Federation for Information Processing (IFIP), and which convened in Montreal, Quebec, Canada in August 2002. WICSA3 is a working conference, with paper sessions for presenting new results from research and practice, and working sessions for identifying new research directions. The papers were organized into five sessions. Two of these sessions, "Dynamic Software Architectures" and "Component-based Architectures", contain papers that focus on a particular architectural style and its properties. The remaining sessions, "Architecture Analysis", "Architecture Description" and "Architecture Reconstruction and Evolution", contain papers that describe new approaches and techniques related to software architecture.