The potential of communication networks and middleware to enable the composition of services across organizational boundaries remains incompletely realized. In this paper, we argue that this is in part due to outsourcing risks and describe the possible contribution of Service-Level Agreements (SLAs) to mitigating these risks. For SLAs to be effective, it should be difficult to disregard their original provisions in the event of a dispute between the parties. Properties of understandability, precision, and monitorability ensure that the original intent of an SLA can be recovered and compared to trustworthy accounts of service behavior to resolve disputes fairly and without ambiguity. We describe the design and evaluation of a domain-specific language for SLAs that tend to exhibit these properties and discuss the impact of monitorability requirements on service-provision practices.