This chapter introduces a Web services-based virtual organization solution, which is designed to enhance the security performance of WSGrid. WSGrid is a “Web services” based application for composing computational grids. A WSGrid environment involves WSGrid-enabled nodes as servers. The virtual organizations are formed by the joint of users and nodes. There is no central component in the system, so every node is individual and has equal position. WSGrid releases full access right to the users, so they can manage their resources. In order to prevent the misuse of flexibility, GateService is proposed. Firstly, a user should be able to access his resources if he can prove his identity. Secondly, he is able to access another’s resources under owner’s permission. Thirdly, long-running processes or crossing-nodes processes should be allowed and executed with only being authenticated at initiation. Finally, Shibboleth no matter cross-domain long-running processes or dynamic delegation should not affect the user’s privacy, the host’s security, and the system’s flexibility. This chapter proposes a security solution for a Web services-based grid application.