Aptitude is a hypernym used in training and practice-based contexts to refer to a person's natural or acquired ability to do something. It tends to be an attribute that is 'forward-looking', i.e. referring to a person's probability of achieving success in the future. This paper adopts a retrospective perspective in looking at the 'success achievement' of (would-be) interpreters and employs the term knowledge, skills and abilities (KSAs). The research questions that this paper addresses relate to frequency of KSAs referred to across four 'stakeholder areas' relevant to interpreter performance: studies from pedagogues on training and (pre-qualification) testing; testing/credentialing authorities; industry-based organisations; and trainee and practising interpreters themselves. Comparison across the four stakeholder areas shows that the training and testing, and credentialing stakeholder areas most frequently identify linguistic and transfer-based KSAs, with moderate attention afforded to intercultural skills, discourse analysis skills, social interactional skills and knowledge bases across different thematic areas, and demonstration of knowledge of ethics. The industry-based stakeholder area records high levels of frequency for KSAs to do with research, terminology, business, self-assessment and ICT skills, alongside linguistic, and interactional KSAs. Overall, however, the broadest spread of frequently identified KSAs is recorded amongst the trainee and practitioner stakeholder group.