This chapter describes synthetic ethology, a scientific methodology in which we construct synthetic worlds in which synthetic agents evolve and become coupled to their environment. First we review the motivations for synthetic ethology as an experimental methodology and explain how it can be used to investigate intentionality and meaning, and the mechanisms from which they emerge, with a special emphasis on communication and language. Second, we present several examples of such experiments, in which genuine (i.e., not simulated) meaningful communication evolved in a population of simple agents. Finally, we discuss the extension of the synthetic ethology paradigm to the problems of structured communications and mental states, complex environments and embodied intelligence, and suggest one way in which this extension could be accomplished. Indeed, synthetic ethology offers a new tool in a comprehensive research program investigating the neuro-evolutionary basis of cognitive processes.