This book constitutes the proceedings of the 4th workshop on Business Process Model and Notation, BPMN 2012, held in Vienna, Austria, in September 2012. The BPMN workshop series provides a forum for academics and practitioners who share an interest in business process modeling using the Business Process Modeling Notation, which is seen by many as the de facto standard for business process modeling. This year, the workshop lasted two days and consisted of both a scientific and a practitioner event. The six full and three short papers presented were carefully reviewed and selected from 22 submissions. The workshop applied a thorough reviewing process, during which each paper was reviewed by three Program Committee members. In addition, an extended abstract of the workshop keynote is also included.