Poststructuralist perspectives on the discursive construction of identity and critical approaches to linguistics, discourse analysis, and language testing have contributed to a growing awareness of the complex social nature of performance in speaking tests. In this article, I explore how the concept of co-construction is useful to understand how candidate and interviewer identities are created in the discourse of speaking tests but argue for an expanded notion of co-construction that draws upon the concept of intertextuality to recognise the myriad of other "voices", representing those who craft the tests, are interwoven into the discourses produced. The study adopts a qualitative approach, drawing upon discourse analysis to examine co-construction and intertextuality in two levels of Cambridge speaking tests. The findings reveal how interviewers and candidates co-construct particular identities through their interaction with each other, the interlocutor frame, and the test materials, and this can account for variability in performance, which is relevant to assessment. The key implications of the analysis for test preparation, interlocutor training, and speaking test development are also discussed.