Interprofessional collaboration involves some kind of knowledge sharing, which is essential and will be important in the future in regard to the opportunities and challenges in practices for delivering safe and effective health care. Nursing assistants are seldom mentioned as a group of health care workers that contribute to interprofessional collaboration in health care practice. The aim of this ethnographic study was to explore how the nursing assistants knowledge can be shared in a team on a spinal cord injury rehabilitation ward. Using a sociomaterial perspective on practice, we captured different aspects of interprofessional collaboration in health care. The findings reveal how knowledge was shared between professionals, depending on different kinds of practice architecture. These specific cultural-discursive, material-economic, and social-political arrangements enabled possibilities through which nursing assistants knowledge informed other practices, and others knowledge informed the practice of nursing assistants. By studying what health care professionals actually do and say in practice, we found that the nursing assistants could make a valuable contribution of knowledge to the team.