The study of dog personality has a long history. In this chapter, we present an overview of the concepts and methods applied to dog personality by reviewing the most recent experimental investigations. Several genetic and environmental factors have been identified that influence dogs’ personality. Understanding the underlying genetic and developmental mechanisms of the dog as a natural animal model for human social behaviour broadens our possibilities to rely on an experimental approach to personality. The research on genetic effects and gene–environment interaction may enable owners and trainers to choose genetically suitable individuals for specific environments.