Objective: To describe and analyze the development and psychometric properties of subjective sedation scales developed for critically ill adult patients., Data Sources: PubMed, MEDLINE, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, CINAHL, Scopus, ISI Web of Science, and the International Pharmaceutical Abstracts., Study Selection: English-only publications through December 2012 with at least 30 patients older than 18 years, which included the key words of adult, critically ill, subjective sedation scale, sedation scale, validity, and reliability., Data Extraction: Two independent reviewers evaluated the psychometric properties using a standardized sedation scale psychometric scoring system., Data Synthesis: Among the 19,000+ citations extracted for the 2013 Society of Critical Care Medicine's Clinical Practice Guidelines for the Management of Pain, Agitation and Delirium and from December 2010 to 2012, 36 articles were identified compassing 11 sedation scales. The scale development process, psychometric properties, feasibility, and implementation of sedation scales were analyzed using a 0-20 scoring system. Two scales demonstrated scores indicating "very good" published psychometric properties: Richmond Agitation-Sedation Scale (19.5) and the Sedation-Agitation Scale (19). Scores with "moderate" properties include the Vancouver Interaction and Calmness Scale (14.3), Adaptation to the Intensive Care Environment (13.7), Ramsay Sedation Scale (13.2), Minnesota Sedation Assessment Tool (13), and the Nursing Instrument for the Communication of Sedation (12.8). Scales with "low" properties included the Motor Activity Assessment Scale (11.5) and the Sedation Intensive Care Score (10.5). The New Sheffield Sedation Scale (8.5) and the Observer's Assessment of Alertness/Sedation Scale (3.7) demonstrated "very low" published properties., Conclusions: Based on the current literature, and using a predetermined psychometric scoring system, the Richmond Agitation-Sedation Scale and the Sedation-Agitation Scale are the most valid and reliable subjective sedation scales for use in critically ill adult patients.