This systematic review aimed to identify thematic elements within definitions of physical and chemical restraint, compare explicit and implicit definitions, and synthesize reliability and validity of studies examining physical and/or chemical restraint use in long-term care. Studies were included that measured prevalence of physical and/or chemical restraint use, or evaluated an intervention to reduce restraint use in long-term care. 86 papers were included in this review, all discussed physical restraint use and 20 also discussed chemical restraint use. Seven themes were generated from definitions including: restraint method, setting resident is restrained in, stated intent, resident capacity to remove/control, caveats and exclusions, duration, frequency or number, and consent and resistance. None of the studies reported validity of measurement approaches. Inter-rater reliability was reported in 27 studies examining physical restraint use, and only one study of chemical restraint. Results were compared to an existing consensus definition of physical restraint, which was found to encompass many of the thematic domains found within explicit definitions. However, studies rarely applied measurement approaches that reflected all of the identified themes of definitions. It is necessary for a consensus definition of chemical restraint to be established and for measurement approaches to reflect the elements of definitions.