This paper discusses Web services synchronization at the composition level. Synchronization aims at assisting independent parties coordinate their actions and thus, avoid conflicts. Our previous work on synchronization primarily focussed on the component level and shed the light on two types of behaviors related to specifying Web services. The operational behavior defines the business logic that underpins the functioning of a Web service, and the control behavior regulates the execution progress of this operational behavior by stating the actions to carry out and the constraints to put on this progress. Operational and control behaviors continue to be used to specify composite Web services with respect to the orchestration schemas that these composite Web services have to comply with whether centralized or peer-to-peer. As a result, various types of messages to achieve synchronization are developed per type of orchestration schema. Experiments showing the use of these messages are reported in this paper as well. Copyright 2009 ACM.