In healthcare settings, suboptimal interprofessional teamwork and communication contribute to unsafe care and avoidable harm. Interprofessional teamwork is essential in high-risk clinical areas such as the emergency department (ED). The aims of this study were to describe interprofessional teamwork in a hospital ED and to evaluate factors influencing interprofessional communication before and after implementation of a department-wide multifaceted intervention. Structured observations were undertaken during 2015/16 and 2019. Differences in interprofessional communication practices, teamwork, and sources of interruptions were compared before and after the intervention. The following domains were surveilled: (a) healthcare professionals (HCPs) communication initiatives, (b) HCPs' contribution to patient assessment, (c) interprofessional communication processes, and (d) team interruptions. The intervention included strategies to enable use of communication tools, changes to team structures, changes in work environment, ethical principles, and establishment of a code of professional conduct during interprofessional communication. Team interruptions significantly decreased post-intervention, and our findings suggest that organizational changes affect domains of teamwork. Statistically significant differences were observed in the initiated communication pre-intervention and contribution to patient assessment significantly increased post-intervention. Multifaceted organizational interventions can positively affect interprofessional team communication and work-flow in the ED, thus patient safety and quality of care can be improved.