Abstract: Starting from the Rational Unified Process RUP and the ARIS life cycle model the ARIS Unified Information System Development Process AUP is designed. Similar as the RUP is developed from the classic waterfall model as an iterative and incremental process to build software, the AUP is developed from the ARIS life cycle model as an iterative and incremental process to build business information systems. As software development is a part of the information system development the RUP is integrated in the AUP. The modeling language for the AUP is a combination of UML and diagrams from the ARIS framework concept.