After a thorough introduction to conscious sedation, including the reasons for the increase in demand for assistance for moderate (conscious)-to-deep sedation in medicine over recent decades, this chapter covers some key definitions, before moving on to morbidity, mortality, and safety. The chapter then discusses how to prepare the patient for sedation, including the issue of whether the patient should have fasted prior to sedation and the screening of patients for sedation. It looks at the necessary qualifications and responsibilities of a sedation practitioner, and the monitoring of patients undergoing moderate-to-deep sedation: this includes monitoring of the ventilation via pulse oximetry, monitoring the efficacy of spontaneous ventilation via capnography, monitoring of the circulation, ECG monitoring, and monitoring the depth of sedation. Routine oxygen administration is also discussed, as are emergency interventions and resuscitation, and recovery and discharge of the patient following moderate-to-deep sedation. The chapter finishes with a discussion of the techniques and drugs used in sedation, and specific considerations surrounding sedation in children.