This article reviews established, emergent, and potential applications of continuous EEG (CEEG) monitoring in the Neuroscience Intensive Care Unit (NICU) and Emergency Department. In each application, its goal as a neurophysiologic monitor is to extend our powers of observation to detect abnormalities at a reversible stage and to guide timely and physiologically sound interventions. Since this subject was reviewed 5 years ago, the use of CEEG monitoring has become more widespread. In a modern NICU, it is no longer novel to have CEEG data contributing to management decisions. A well-trained CEEG monitoring team is important for its optimal implementation. In the diagnosis and management of convulsive and nonconvulsive status epilepticus, its value appears established. It is finding benefit in the early diagnosis and management of precarious cerebral ischemia, including severe acute cerebral infarctions and post-SAH vasospasms. In comatose patients, it can provide diagnostic and prognostic information which is otherwise unobtainable. More recently, it has been found advantageous for targeting management of acute severe head trauma patients. Networking technology has facilitated the implementation and oversight of CEEG monitoring and promises to expand its availability, credibility, and effectiveness. The maturing of CEEG use is reflected in preliminary efforts to assess its cost benefit, cost effectiveness, and impact on patient outcomes.