This paper is based on Siemens extensive experience in the area of quality for software-based products, systems, and plants. It describes the "best practices" in the area of software and quality that are used at Siemens. These techniques include Siemens' approaches in the areas of assessments and improvement of development processes, the use of metrics to measure such improvements, testing and quality engineering, inspections and reviews, software architecture as well as organization issues associated with quality such as the sharing of best practices in these areas. The results are based on a number of examples from a broad variety of application areas (e.g. telecommunications, industrial automation, medical engineering and transportation). Our experience is that a focus on quality leads to reductions in cycle-time, effort, and costs and thus to business benefit.