This chapter provides an overview of several formal approaches for the design, specification, and verification of interactive systems. For each approach presented, we describe how they support both modelling and verification activities. We also exemplify their use on a simple example in order to provide the reader with a better understanding of their basic concepts. It is important to note that this chapter is not self-contained and that the interested reader should get more details looking at the references provided. The chapter is organized to provide a historical perspective of the main contributions in the area of formal methods in the field of human–computer interaction. The approaches are presented in a semi-structured way identifying their contributions alongside a set of criteria. The chapter is concluded by a summary section organizing the various approaches in two summary tables reusing the criteria previously derived.