Book excerpt: Jan Recker investigates the notion of quality of business process modeling grammars. His evaluation is based on ontological analysis, qualitative analysis, and quantitative analysis, which are applied to BPMN, a widely used business process modeling grammar. His results first show ontological shortcomings in BPMN, second how these manifest in actual process modeling practice, and third how they eventually influence the usage behavior of modeling practitioners. Seen more general, his book is a landmark for an empirical technology assessment that analyzes how design flaws in technology influence usage behavior.