Abstract This paper describes ASCET-SD, a development environment for embedded control systems. Using a new approach, involving flexible modeling, automatic code generation, and offline as well as online simulation, ASCET-SD supports every step of the development process. After a discussion of the development process for embedded control systems, the different kinds of modeling supported by ASCET-SD are presented in detail. The novel features are the support for several modeling philosophies, controller refinement and optimization adapted for use in the embedded control design. The next main point described in the paper is the automatic code generation supported by ASCET-SD, which closes the time-consuming and expensive gap between flexible algorithm development, prototyping and series production. Finally, an overview is given of the whole experimentation environment, the experimental hardware, the database management and the documentation generator.