Frailty is an important concept in aging research and care. Awareness of frailty signs allows healthcare workers to identify older adults at risk and design interventions to prevent their functional decline, therefore preventing adverse health outcomes. This literature review allows to identify predictors of frailty considering its physical, psychological and social domains. From the evidence found, it is possible to formulate a profile of fragile older people. Finally, future research should focus on the description of psychological and social fragility profiles, on the detection of persons likely to be fragile and finally to define precise instruments to detect fragile people, which should become the gold standards in future research.