Reactive distillation (RD) is a widespread process intensification method that combines reaction and separation into a single unit, which allows the simultaneous production and removal of products. This improves productivity and selectivity, reduces energy use, eliminates the need for solvents, and leads to intensified and highly efficient systems with green engineering attributes. Some of these key benefits are realized by using the reaction to improve separation, whereas others are obtained by using the separation to improve reaction performance. This chapter addresses the working principles, modeling, design, control, and applications of RD. Several industrial case studies are provided to illustrate the key features of RD processes.