It has been previously demonstrated that interactions within interprofessional teams are characterised by effective communication, shared decision-making and knowledge sharing. This paper outlines aspects of an action research study examining the emergence of these characteristics within change management teams made up of nurses, general practitioners, physiotherapists, care assistants, a health and safety officer and a client at two residential care facilities for older people in Ireland. The theoretical concept of Team Psychological Safety (TPS) is utilised in presenting these characteristics. TPS has been defined as an atmosphere within a team where individuals feel comfortable engaging in discussion and reflection without fear of censure. Study results suggest that TPS was an important catalyst in enhancing understanding and power sharing across professional boundaries and thus in the development of interprofessional teamwork. There were differences between the teams. In one facility, the team developed many characteristics of interprofessional teamwork while at the other there was only a limited shift. Stability in team membership and organisational norms relating to shared decision making emerged as particularly important in accounting for differences in the development of TPS and interprofessional teamwork.2