This book constitutes the refereed proceedings of the Third International Workshop on Web Services and Formal Methods, WS-FM 2006, held in Vienna, Austria in September 2006 in conjunction with the Fourth International Conference on Business Process Management, BPM 2006.

The 15 revised full papers presented together with 3 invited lectures were carefully reviewed and selected from 40 submissions. The main topics of include: protocols and standards for WS (SOAP, WSDL, UDDI, etc.); languages and description methodologies for Coreography/Orchestration/Workflow (BPML, XLANG and BizTalk, WSFL, WS-BPEL, etc.); coordination techniques for WS (transactions, agreement, coordination services, etc.); semantics-based dynamic WS discovery services (based on Semantic Web/Ontology techniques or other semantic theories); security, performance evaluation and quality of service of WS; semi-structured data and XML related technologies.