Words classified as ‘interjections’ tend to be treated in descriptive grammars as outside of morphosyntax, too contextually bound to warrant a systematic description of their syntagmatic relations. In this paper we argue that if one takes grammar to include recurrent patterns in conversational turns that are routinely connected with particular interactional functions, such as assessments and acknowledgements, then the grammar of interjections can indeed be incorporated into language description in ways that show the systematic relationships between form and function. We use a comparative corpus of conversations in four typologically distinct Australian Aboriginal languages (Garrwa, Gija, Jaru and Murrinhpatha) to illustrate how such an analysis may be developed. We focus on forms which have been described as ‘compassionate interjections’, which express that the speaker takes a compassionate affective stance towards something described in prior talk or evident in the situation. Despite differences in the morphological properties of these words in the languages we compare here, they display remarkable similarities in where they occur within conversational turns, and the functions they serve in different turn-related positions.