Resource brokering in Grids is nowadays handled by resource brokers that require detailed knowledge of the state of the resources that they broker. In business settings, surrendering internal information on resources to an outside party is not an option. The traditional resource brokering method based on intimate resource knowledge is therefore not a viable possibility. This paper argues that the publication of resource state data is not needed for resource brokering. Instead, we advocate the use of service level agreements (SLAs). The use of SLAs for brokering lets providers keep state information internal and at the same time provides customers with guarantees on the used services. The proposed model has been implemented in the form of a resource broker that is based on Web Service technology. It shows that the approach of using SLAs for scheduling is a possible solution to keeping resource state private. Categories and Subject Descriptors D.4.7 [Organization and Design]: Distribute...