Grid computing allows sharing of services and resources distributed over geographically dispersed, heterogeneous, autonomous administrative domains. As a domain generally has no idea about the trustworthiness of other domains, it may hesitate in accessing shared services and resources provided by other domains. Accessing resources and services from untrusted domains may pose dangerous consequences to the source domain. Trust is an important parameter in achieving faithful domain to domain interaction. Domains must be able to determine the trustworthiness of each other for the access of a particular service. Domains must also provide trust based access to resources and services that they expose in the environment. This paper describes different facets associated with trust issues among different entities in a grid environment and proposes a trust model to establish and manage trust relationships. The trust model provides support to calculate direct as well as recommended trust. Based on this model, a trust based authorization framework is proposed that can be used to provide trust based access to grid services. The goal of the model is to encourage trust based domain to domain interaction and increase the confidence of domains in accessing shared resources provided by other domains. The framework has been implemented in .NET environment with the support of WSE 3.0 toolkit. The framework has been evaluated by implementing a scenario that involves enforcement of different trust policies. The time taken by the enforcement component to evaluate trust policies has been noted. The results obtained from the implementation imply that the approach is workable and can be used to provide trust based access to grid services.