Service Oriented Architecture (SOA) is an approach for building distributed systems that deliver application functionality as a set of self-contained business-aligned services with well-defined and discoverable interfaces. This paper presents a systematic and architecture-centric framework, named Service Oriented Architecture Framework (SOAF), to ease the definition, the design and the realization of SOA in order to achieve a better business and IT alignment. The proposed framework is businessprocess centric and comprises a set of structured activities grouped in five phases. It incorporates a range of techniques and guidelines for systematically identifying services, deciding service granularity and modeling services while integrating existing operational/legacy systems. The results from a pilot validation of SOAF for SOA enablement of a realistic Securities Trading application are presented. Best practices and lessons learned are also discussed.