In this chapter we present a first survey of laboratory studies using communication. We first discuss a number of issues about the implementation of communication in the laboratory. In particular, we discuss variations in the channels, the structure and the content analysis of communication. Second, we survey a number of studies in which the effects of free-form communication are compared to those with more restricted communication. We finish with a brief reference to the question of why communication matters. In other words, what are the mechanisms through which communication affects behavior?.