The construction of composite Web Services from service fragments requires semantic descriptions of service offers and service requests. We propose the use of dependencies as a modeling concept to describe service requests and service offers and outline a Web Service Market, that constructs composite services, offered by a temporary network of economically independent service providers, by resolving dependencies based on coordination theory. Categories and Subject Descriptors C.2.4 [Computer-Communication Networks]: Distributed Systems - distributed applications General Terms Design, Economics, Experimentation, Security Keywords Coordination, Semantic Web, Web Services