Objective Nurses are vital in providing and improving quality of care. To enhance the quality improvement (QI) competencies of nurses, hospitals in the Netherlands run developmental programmes generally led by internal policy advisors (IPAs). In this study, we identify the roles IPAs play during these programmes to enhance the development of nurses' QI competencies and studied how these roles influenced nurses and management. Design An exploratory ethnographical study comprising observations, informal conversations, semistructured interviews, focus groups and a strategy evaluation meeting. Setting A teaching hospital in an urban region in the Netherlands. Participants IPAs (n=7) in collaboration with four teams of nurses (n=131), team managers (n=4), senior managers (n=4) and the hospital director (n=1). Results We identified five distinct advisory roles that IPAs perform in the hospital programme: gatekeeper, connector, converter, reflector and implementer. In describing these roles, we provide insights into how IPAs help nurses to develop QI competencies. The IPA's professional background was a driving force for nurses' QI role development. However, QI development was threatened if IPAs lost sight of different stakeholders' interests and consequently lost their credibility. QI role development among nurses was also threatened if the IPA took on all responsibility instead of delegating it timely to managers and nurses. Conclusions We have shown how IPAs' professional background and advisory knowledge connect organisational, managerial and professional aims and interests to enhance professionalisation of nurses.