Grid computing is a technology that offers the opportunity to share IT-resources between departments in organizations as well as between different organizations. Thereby adopters may obtain significant advantages like cost reduction and efficient IT-resource load balancing. Nevertheless this technology is not established in the industry by now. We developed an adoption model to measure the major factors which are influencing adoption of Grid computing in an organizational environment. As Grid computing is an inter-organizational system providing both inter- and intra-organizational linkages our adoption model accounts for both areas of influence factors. The inter-organizational influence factors were based on a model proposed by Teo et al. (2003) who reverted to the institutional theory. Mimetic-, coercive- and normative pressures exerted by surrounding organizations like suppliers, customers and competitors are representing the inter-organizational influence factors in our adoption model. Following the organizational capability-based theory we included intra-organizational influence factors which consist of IT-related factors, the innovativeness of an organization and the attitude towards outsourcing of IT-resources. Using structural equation modeling our adoption model identified mimetic pressures (emerging from competitors), the innovativeness and the attitude towards outsourcing of IT-resources as factors with significant positive influence on the adoption of Grid computing.