This Special Section of J-DEDS on Modeling of Reactive Systems was inspired by the eighth edition of the French-speaking conference “Modélisation des Systèmes Réactifs—MSR 2011.” MSR 2011 was organized by the LAGIS (Laboratoire d’Automatique, Génie Informatique et Signal) and LIFL (Laboratoire d’Informatique Fondamentale de Lille) laboratories, and held at École Centrale de Lille, France, on November 16–18, 2011. MSR is a conference that traditionally gathers French-speaking researchers from both the Computer Science and the Automatic Control communities, and that are involved in the modeling, analysis and control of reactive systems. [...]