This paper describes GRASS, an object-oriented framework for SCADA (Supervisory Control And Data Acquisition) systems. The proposed framework consists of class libraries and tools, that support development of SCADA system software. The basic functional requirements of SCADA systems are similar, regardless of the particular application field, so substantial software sharing is possible. Nevertheless, productivity of SCADA software is impeded by dependence on details of the target system. The task of configuring the SCADA software for each target system is complex, typically involving manual input of a lot of system description data. GRASS simplifies this task by automatically generating system description data and providing editing tools for subsequent customization.