The paper seeks to identify how teacher expertise is implicitly and explicitly conceptualised in current English education policy in respect of the professional development of teachers. We focus specifically on conceptualisations of expertise in the Early Career Framework (ECF), both in terms of the policy documentation produced by the Department for Education and in terms of a selection of publicly available materials produced by the lead providers of the ECF. We aim to locate these conceptualisations in terms of broader sociological and philosophical debates about the nature of expertise and its relationship to professional work, in addition to recent research on the policy context of teacher education and professional development in England. Our analysis reveals the inappropriacy of 'expert systems' approaches to expertise in educational contexts, the underlying assumptions embedded in policy in terms of what constitutes high-quality teaching practice and the insufficiency of relying on an appointed advisory group and organisations preferred by government for identifying and iterating criteria for expertise.