Reactive scripts are designed to get a flexible approach for responsive systems; they are based on the reactive/synchronous approach, well suited to real time programming. A reactive script interpretor is a broadcast event-driven interpreter which can react to several commands in parallel. Generating events and waiting for occurrence of events are the basic commands which are composed in several ways to build complex behaviors. The basic principle is that absence of an event cannot be decided before the end of the current interpretor reaction. One can define objects with associated methods (behaviors), run when a nonblocking order is sent to them. Method execution is immediate (in the same interpreter reaction as the order) and a method can be executed at most once during each reaction. Reactive scripts are a mix of two formalisms: the SL synchronous language, and the ROM Reactive Object Model. Reactive script interpreters are implemented using the Reactive-C language.