AbstractThis article examines the themes of policy advice, expertise, and policy advisory systems. It argues that persistent challenges and more emergent trends involving their intersection can be effectively understood through the lenses of instrumentality, authority, and adaptability. In the wake of renewed questions about the continued viability of longstanding public administration advisory arrangements, these themes help locate new pressures on those arrangement such as those linked to technological developments, shifting conceptions of expertise, and growing recognition of the challenges of managing systems of advice. These themes help facilitate continued engagement with persistent challenges linked to adequate policy capacity, the role of the public service advice, and question of rigour, legitimacy, and the democratic contexts of policy advising.Points for practitioners Technological innovations and turbulent governance arrangements have renewed debates around technocracy, democratic control and participation, the role of evidence, and normative and ethical considerations inherent in the generation and use of policy advice. Policy capacity remains important for well‐functioning policy advisory systems. It has itself become multifaceted reflecting not only important differences in types of expertise and policy advice, but also concerns around its management and deployment in varying governance contexts. The competencies required for policy workers inside and outside of government should reflect changes in the role of expertise and evolving systems of policy advice.