Virtual Enterprises or Organisations (VO) have been the focus of research for over a decade1. Although proprietary implementations of VO management tools exist, secure tools based on interoperating open standards are not yet available. The open standards on which to build them are just being released as reliable implementations. The requirements of VOs for trust and security are presented, which lead to an architecture for a secure VO management framework. The design of such a framework is analysed to show how the current open Web Service specifications could be used to implement it in practice. The need for the reliable and interoperable implementation of these essential Web Services specifications is advocated.