Assessing the correct operation of individual web services or of entire business processes hosted on a Service Oriented Architecture (SOA) is one of the major challenges of SOA research. The unique features of WS/SOA require new quality assessment approaches, including novel testing and monitoring techniques. In this paper, we present a framework for assessing the correct functioning of WS/SOA systems by introducing a third party certifier as a trusted authority that checks and certifies WS/SOA systems. Our certifications are based on signed test cases and their respective results and operate at different level of granularity, providing a sound basis for run-time service selection and process orchestration decisions.