The paper presents a comprehensive and integrated approach for business process modeling and for the specification of distributed business application systems. The approach is based on a framework of business systems which consists of three layers: (1) business process model, (2) business application systems, and (3) computing systems. This framework is used to manage the complexity of a business system and to address the different actors and abstractions of actors within a business system (e.g. persons and machines, application systems, and computing systems). The linkage of the layer of business application systems to both the layers of business processes and computing systems helps to specify the distribution of business application systems in a natural way. Object-oriented concepts are used as universal enabling techniques.