This cluster of papers explores the concept of interactional expertise, particularly in the context of knowledge exchange, ethical decision-making, and practice in fields such as dementia care, healthcare, and social science. It delves into the nuances of tacit knowledge, ethical guidelines for lying in healthcare, and the embodiment of expertise. The cluster also discusses the application of interactional expertise in technical decision-making and the relevance of phronesis and pragmatism in various domains.