The present study explored authorial presence in the abstracts across three purpose-built discipline-specific corpora of RAs in major but relatively less represented disciplines in corpus studies: Civil Engineering (CE), Political Sciences (PS) and Veterinary Medicine (VM). In particular, due to less attention having been paid to these fields, we examined explicit authorial references with a functional perspective in a corpus of abstracts totaling over one million words. To this end, we first conducted a preliminary search for explicit third-person plural author references in the corpora and manually analysed a total of over 6,000 instances to check if they were all markers signaling an authorial presence in the text. Following this, the second manual analyses concentrated on categorizing the rhetorical functions of self-mentions based on Xia’s (2018) framework. The preliminary findings showed that the frequency of “we”-based authorial references in PS outweighed that in the other disciplines (PS: 722.13; CE: 636.81; VM: 481.30 per 100,000 words). Regarding the density of authorial references, we found that each discipline favored being more visible with divergent authorial roles in their abstracts. For example, PS were more rhetorically present in their abstracts by “proposing a theory or approach” whereas CE and VM authors used fewer self-mentions to mark their presence frequently with this rhetorical device. With respect to the functional analyses of the self-mentions of “we”, all three disciplines displayed more low-stakes functions such as “recount experimental procedure and methodology”. We focused on the significance of cross-disciplinary and functional analysis in the study in order to contribute to designing activities in EAP for each discipline.