The development of effective guidelines for psychosocial care of family members who accompany a critically ill person into the emergency department (ED)is both complex and challenging. Guidelines must accommodate the specific cultural features of clinical practice in the ED, and incorporate an understanding of the perspectives of family member recipients of care and the clinicians expected to implement their care. The aim of this three stage study was to develop ecologically valid, evidence based guidelines for the psychosocial care of family members who accompany a critically ill person into the ED. Understanding of family needs, the interactions between different members of the ED team, and the impact of behaviours on family outcomes were used to inform strategies to improve the quality of clinical practice. The outcomes of this study also inform processes for developing sensitive practice guidelines for complex environments such as the ED.