Thorough assessment and support of cardiopulmonary function are essential in caring for every patient in the pediatric cardiac intensive care unit (CICU). The patient population in the CICU ranges from the preoperative patient awaiting cardiac surgery, the child with congestive heart failure, cardiomyopathy, or arrhythmias to the postoperative patient who has undergone palliation or corrective surgery for congenital heart disease. Nurses working in this environment must have exceptional assessment skills, clinical expertise, and a sound judgment to respond to constantly changing and potentially emergent situations. In addition, with the practice of holistic family-centered care, nurses must extend compassion and empathy to each child as well as to their parents, and extended family throughout their experience in the CICU. This chapter outlines basic cardiac assessment essential for the critical care nurse and defines clinical skills needed to care for the pediatric medical and surgical cardiac patient. The developmental needs of children in the CICU will be discussed within the context of a family-centered environment of care.