This book contains the refereed post-conference proceedings of the First International Self-Organizing Architectures Workshop (SOAR) in Cambridge, UK, in September 2009. The book includes 9 revised papers, which were selected from 17 submissions of the workshop, as well as 4 invited papers. The papers cover a broad range of topics related to self-organizing architectures, including self adaptive architectures, decentralized architectures, nature-inspired approaches, and learning approaches.