A Multi-Organization Environment is composed of several players that depend on each other for resources and services. In order to manage the security of the exchange process we introduce the concept of trust. We show how this aspect of the cooperative work allows us to increase some security aspects. In particular, we provide a framework where the concepts of trust requirement and trust evaluation play important roles for defining trust vectors. These vectors evaluate a set of requirements, under some conditions, and provide a degree of confidence. In our framework we consider two different types of vectors. On the one hand a vector that relates a user to an organization and on the other hand a vector that links two organizations. Finally we show how these vectors are evaluated and shared among the different organizations, and how we combine the provided trust information in order to enhance the security.