Service-oriented systems have attracted great interest from industry and research communities worldwide. Service integrators, developers, and providers are collaborating to address the various challenges in the field. PESOS 2010 is a forum for all these communities to present and discuss a wide range of topics related to service-oriented systems. The goal of PESOS was to bring together researchers from academia and industry, as well as practitioners working in the areas of software engineering and service-oriented systems to discuss research challenges, recent developments, novel applications, as well as methods, techniques, experiences, and tools to support the engineering and use of service-oriented systems.