This research develops a new Theatre and Performance A level for upper-secondary schools in England. Observing the language of professional rehearsals and analysing select philosophies of process and experience leads to a conceptual framework that is recontextualised to new curriculum documents. Using Bernstein’s recontextualisation, it traces the transformational journey knowledge takes from theatre’s academic and professional discipline to the pedagogic site of a Key Stage 5 qualification. The first phase identifies five problematic forms of knowledge recontextualisation in the current Drama and Theatre A level using Fairclough’s Critical Discourse Analysis: risk, narrowness, simplification, compartmentalisation, and distortion. This thesis contends that the closed, definitive, and replicable theatre studied by A-level students is disconnected from the professional and academic discipline, in contrast to Ofqual’s assertions. The second phase attempts to reconnect the A level with theatre’s openness, ambiguity, and experimentation by observing rehearsals of Crouch’s Total Immediate Collective Imminent Terrestrial Salvation, MacLaine’s vessel, and Mahfouz’s A History of Water in the Middle East and analysing the influential philosophies of Eco, Barthes, Merleau-Ponty, and Deleuze. Using a method based on Marsden’s rehearsal studies and Tracy and Craig’s Action Implicative Discourse Analysis, word cloud and creative writing posters capture a portrait of their practice and lead to articulating situated ideals. These are collected alongside concepts constructed from the language of the philosophies to build a conceptual framework for a new Theatre and Performance A level. The common features of relationality, multiplicity, uncertainty, and changeability are recontextualised to new assessment objectives that, in turn, inform new subject content and specification documents. The third phase analyses this new, connected curriculum using Hughes’ Positive Discourse Analysis to show how the problematic forms of knowledge recontextualisation are minimised. The new understanding of theatre’s disciplinary knowledge facilitates an engagement with a rich-knowledge that is relational, multiple, uncertain, and changeable.