A workplace-based assessment (WBA) is a learning recording device that is widely used in medical education globally. Although entrenched in medical curricula, and despite a substantial body of literature exploring them, it is not yet fully understood how WBAs play out in practice. Adopting a constructivist standpoint, we examine these assessments, in the workplace, using principles based upon naturalist inquiry, drawing from a theoretical framework based on Goffman's dramaturgical analogy for the presentation of self, and using qualitative research methods to articulate what is happening as learners complete them. Learners were voluntarily recruited to participate in the study from a single teaching hospital. Data were generated, in-situ, through observations with field notes and audiovisual recording of WBAs, along with accompanying interviews with learners. Data from six learners was analysed to reveal a set of general principles-the WBA playbook. These four principles were tacit, unwritten, unofficial and learners applied them to complete their WBA proformas: (1) maintain the impression of progression, (2) manage the authenticity of the individual proforma, (3) avoid losing face with the assessor and (4) complete the proforma in an effort-efficient way. By adhering to these principles, learners expressed their understanding of their social position in their world at that time the documents were created. This paper recognises the value of the WBA as a lived experience, and of the WBA document as a social space, where learners engage in a social performance before the readers of the proforma. Such an interpretation better represents what happens as learners undergo and record WBAs in the real-world, recognising WBAs as learner-centred, learner-driven, meaning-making phenomena. In this way, as a record of interpretation and meanings, the subjective nature of the WBA process is a strength to be harnessed, rather than a weakness to be glossed over.