Caviomorph species are well known for their social nature and variety of vocal sounds used in intra-species communication, making them ideal candidates for the study of vocalisations. Here, I provide a much needed categorisation for one such species, the Degu Octodon degus. By analysing 3535 vocal sounds, I demonstrate that there are 15 distinct categories for degu vocalisations, showing that degus have a wider and more complex vocal repertoire than was previously assumed. I find that the use of vocal sounds varies widely with season and behavioural context, consistent with interaction in a complex social hierarchy. I identify that certain categories are not used by pups and that others may be gender-specific. In addition, I find that vocalisations used by lactating females may have an alternative function to that previously assumed. By examining the frequency range of the vocalisations identified, I predict that the hearing range of the degu lies between 71 Hz to 21.7 kHz. Finally, I describe the structure, causation and likely function of each vocal type.