Whether seeing a patient in the ambulatory clinic environment, performing a delivery or managing a critically ill patient, obstetric care is a team activity. Failures in teamwork and communication are among the leading causes of adverse obstetric events, accounting for over 70% of sentinel events according to the Joint Commission. Effective, efficient and safe care requires good teamwork. Although nurses, doctors and healthcare staff who work in critical care environments are extremely well trained and competent medically, they have not traditionally been trained in how to work well as part of a team. Given the complexity and acuity of critical care medicine, which often relies on more than one medical team, teamwork skills are essential. This chapter discusses the history and importance of teamwork in high-reliability fields, reviews key concepts and skills in teamwork, and discusses approaches to training and working in teams.