The Service-Oriented Architecture paradigm (SOA), e.g., realized with Web Services technology, enables enterprises to establish cross-organizational, service-based workflows. An important issue is the monitoring of the fulfillment of Service Level Agreements (SLAs) which define the responsibilities between the participants. Recent research has shown that agent technology is a useful approach in this context. Thus, we present ways for agent cooperation on different levels of abstraction. This cooperation aims at monitoring workflows and especially to react to deviations in different scenarios of SLA violations.