ABSTRACTBackground:The goal of the study was to analyze the factors associated with quality of life (QoL) in institutionalized older adults with dementia, based on self and proxy ratings, and if these characteristics differ by dementia severity.Methods:Cross-sectional study of 525 people with dementia (PwD) and their caregivers (professional or family caregivers). Two different QoL questionnaires, leading to three measures, were used: QoL in Alzheimer's disease scale (QOL-AD), self and proxy-rated, and QoL in late-stage dementia scale (QUALID), proxy-rated. Multivariate linear regression models were tested for each QoL measure and for mild/moderate and severe stages of dementia.Results:Multiple regression analyses showed a significant association between the three QoL measures and depression. Functional ability was significantly associated with QoL when assessed by proxy. Other factors such as education level, leisure activities and frequency of visits were significantly related with QOL-AD by proxy. The associated factors that differed by dementia severity were education level for moderate dementia, and frequency of visits and who answered the questionnaire (professional vs. family member) for severe dementia.Conclusions:QoL was consistently associated with depressive symptoms independently of the measures as well as functional ability and social leisure activities when the QoL questionnaire was rated by proxy. Treating depressive symptoms, increasing social activities and maintaining the functional ability may decrease the deterioration of QoL in institutionalized older adults with dementia.