The objective of this research work is to look into the role of policies and context in framing the composition of Web services. Context supports the development of adaptable Web services and policies specify the behavior of Web services engaged in composition. In this paper, we present this research work's outcome, namely a context-based multi-type policy for Web services composition in which the binding between Web services occurs at four levels: component level to deal with Web services' definitions and capabilities, composite level to address how Web services are discovered and combined, semantic level to handle the semantic heterogeneity that can arise between Web services, and resource level to focus on the performance of Web services. Because of the composition complex-nature, the proposed approach uses three types of policies: engagement policies assess a Web service participation in a given composition, mediation policies deal with the semantic heterogeneity by tacking into account the mappings and conversions between component Web services, and deployment policies manage the interactions between component Web services and computing resources. Policies manage the transitions between the four levels and context caters the necessary information that tracks the composition progress. © 2006 Elsevier B.V. All rights reserved.