This paper identifies current UK policy for exploring both competence and expertise. It is argued that the purpose of assessing competence and expertise is relevant in deciding the approaches used. Different perspectives about competence, specifically those that have arisen in the United States and the United Kingdom, are considered in relation to how competencies may be developed and assessed. The different terms used in discussion about competency are also discussed. From the literature, criteria for selecting experts in nursing, the attributes of expertise and enabling factors are presented in relation to how expertise in practice may be judged. The pilot recognition process and development of evidence for the Royal College of Nursing's Expert Practice Project, together with its facilitation through critical companionship, are described. It is concluded that the processes necessary for demonstrating expertise in practice are consistent with the recognition that the attributes of expertise are interdependent, complex and situational. Critical companionship provides a mechanism which is primarily developmental and supportive, but focuses on practice development and practitioners' effectiveness and can result in the development of evidence for a range of different purposes such as demonstrating expertise, as well as practice development, service development and career progression.