Many companies have adopted Process Aware Information Systems (PAIS) for supporting their business processes in some form. On the one hand these systems typically log events (e.g., in transaction logs or audit trails) related to the actual business process executions. On the other hand explicit process models describing how the business process should (or is expected to) be executed are frequently available. Together with the data recorded in the log, this raises the interesting question "Do the model and the log conform to each other?". Conformance testing, also referred to as conformance analysis, aims at the detection of inconsistencies between a process model and its corresponding execution log, and their quantification by the formation of metrics. This paper proposes an incremental approach to check the conformance of a process model and an event log. At first, the fitness between the log and the model is ensured (i.e., "Does the observed process comply with the control flow specified by the process model?"). At second, the appropriateness of the model can be analyzed with respect to the log (i.e., "Does the model describe the observed process in a suitable way?"). Furthermore, this suitability must be evaluated from both a structural and a behavioral perspective. To verify the presented ideas a Conformance Checker has been implemented within the ProM framewor
