This volume presents the set of papers accompanying the lectures of the 9th International School on Formal Methods for the Design of Computer, Com- nication and Software Systems (SFM). Thisseriesofschoolsaddressestheuseofformalmethodsincomputerscience asaprominentapproachtotherigorousdesignofcomputer,communication,and software systems. The main aim of the SFM series is to o?er a good spectrum of current research in foundations as well as applications of formal methods, which can be of help for graduate students and young researchers who intend to approach the ?eld. SFM 2009 was devoted to formal methods for Web services and covered s- eral aspects including choreography, orchestration, description techniques, - teraction, synthesis, composition, session types, contracts, veri?cation, security, and performance. This volume comprises eight articles. Bruni’s paper overviews some of the most recently proposed abstractions in the setting of process calculi tailored to the well-disciplined handling of issues such as long-running interactions, orch- tration, and unexpected events. Van der Aalst, Mooij, Stahl, and Wolf provide some foundational notions related to service interaction and address in a Petri net setting challenges like how to expose a service, how to replace and re?ne services, and how to generate service adapters. The paper by Marconi and - store presents a survey of existing approaches to the synthesis of Web service compositions, a di?cult and error-pronetask that requires automated solutions.