Safety-critical systems are a subclass of reactive systems, a dominating class of computer systems. Such systems control airbags in cars, flaps of aircrafts, or pace makers. Software for these systems must be reliable. Hence, a language and tooling is needed that allows to build and maintain reliable software models. Furthermore, a reliable compiler is required to obtain decent machine-understandable and executable code from highly abstract models. This thesis presents SCCharts, a Statecharts-based visual and synchronous modeling language for specifying and designing safety-critical software systems and for deriving their implementations. http://www.sccharts.com