Several authors report failures when using diagrams with a defined notation for participatory design processes. Our experience in various projects was different: diagrams with graphical notations are artefacts which can be used participatively to design socio-technical systems. In this paper we describe our experience from two proj ects where models of socio-technical systems are designed participatively. The used methods are based on a special view on socio-technical systems. Both theory and case studies provide the basis to derive relevant factors for the process and the notation to enable participation in projects where modelling methods are used.
