INCOME/STAR is an experimental environment for the cooperative development of distributed information systems. This paper presents some of INCOME/STAR's innovative features in the area of information systems engineering:First a new type of high-level Petri nets, so-called Nested Relation/Transition nets (NR/Tnets), is described. NR/T-nets allow the modeling of concurrent processes and related complex structured objects in distributed business applications.New concepts for entity and relationship clustering were developed to support a stepwise topdown approach for Entity/Relationship based object modeling. Distributed multi-user simulation and prototyping are used for the evaluation and analysis of NR/T-nets and the involved object schema.Finally, ProMISE -an evolutionary process model for information system development -is introduced. A role-based groupware component is part of the INCOME/STAR architecture to support communication, organization and social interaction in development projects.