STEP (ISO 10303) is becoming the standard in the process industries for electronic information exchange. To help in the integration of STEP based tools, a process plant engineering activity model has been produced by the PISTEP (Process Industries STEP) consortium. The model provides an overview of-the main activities and data flows associated within the process plant life cycle. The model is written as a guideline and can be tailored to meet the particular requirements of a project.This paper describes a computer based project management system (Plantool) that is able to handle activity models within a concurrent engineering framework. The system supports the development and change of an activity model whilst a particular project is being undertaken.