This chapter presents empirical studies that have tested children’s ability to understand implicatures. It starts with the category of relevance implicatures, before moving to scalar implicatures. In both cases, the conclusion is that even young children during the preschool years have the ability to derive implicatures when the task is kept simple enough. The chapter then presents studies that have focused on cases of atypical development, such as autism spectrum disorders, SLI and deafness.