Evaluation of modelling languages is important both to be able to select the most suitable languages according to the needs and to improve existing languages. In this chapter, business process modeling notation (BPMN) is presented and analytically evaluated according to the semiotic quality framework. BPMN is a functionally oriented language well suited for modeling within the domain of business processes, and probably general processes outside of the business domain. The evaluation indicates that BPMN is easily learned for simple use, and business process diagrams (BPDs) are relatively easy to understand. Tools can fairly easily map BPDs into the Web Services Business Process Execution Language (WS-BPEL) (formerly known as BPEL4WS) format, but executable systems then require creation of Web services representing the activities in BPDs. An evaluation according to the Bunge-Wand-Weber (BWW) ontology is useful for finding ontological discrepancies, and the semiotic framework is useful for evaluating quality on a relatively general level. Thus, these methods complement each other.