Grinding is a final step in the production chain of gears and therefore determines the quality of the product. In the industrial practice gears are cut - generally by means of a hobbing process - and their surface is hardened through a heat treatment, which has the target of increasing the wear resistance of the tooth flanks. Grinding is therefore necessary to remove the material distortions originating during the heat treatment and to fulfill dimensional and quality requirements. Usually only gears with high quality requirements are ground. Otherwise grinding is not carried out to reduce the production costs. In the recent years however the percentage of ground gears has been growing continuously due to the rising demands on load capacity, quiet running and life time as well as the increasing performance offered by the grinding processes. Generating grinding by means of cylindrical grinding worms shows the highest potential among the existing processes for gear grinding due to the high material removal performance that can be achieved. In order to use dressable worms efficiently the dressing technology has to be optimized. The present contribution describes the technology for dressing vitreous bonded grinding worms. This process is based on the use of form dressing rollers by means of which the grinding worm geometry and topography are generated. The investigations are aimed at analyzing the influence of the dressing parameters, in particular the speed ratio between dressing and grinding tool, and the attainable gear quality and surface properties. The results show significant dependencies between the dressing strategy and the grinding results.