Background <p>Delirium is a common yet often underdiagnosed neuropsychiatric syndrome among older adults, especially those residing in the home setting or in residential care. It has been associated with elevated risks of morbidity, mortality, and institutionalization. While delirium has been extensively studied in hospital settings, its prevention and risk factors in the home setting and residential care setting remain insufficiently investigated.</p> Objectives <p>This review investigates the prevalence, risk factors, and preventive interventions for delirium among older adults residing in the home setting and in residential care, including assisted home care facilities and nursing homes.</p> Methods <p>A scoping review was undertaken, including studies of individuals aged ≥ 65&#xa0;years diagnosed with delirium through validated assessment tools (e.g., DSM, ICD). Eligible studies were to have a primary emphasis on the prevalence, associated risk factors, or preventive strategies related to delirium. Data on study characteristics, methodological approaches, and key findings were extracted and synthesized in a narrative format, supplemented by tables and figures.</p> Results <p>Sixty studies fulfilled the inclusion criteria. Reported delirium prevalence ranged from 0.1% to 44.0% in the home setting and from 1.0% to 70.3% in residential care. Key risk factors associated with delirium in the home setting and in residential care included cognitive impairment, the presence of dementia, and level of dependence, while age was generally not found to be significantly associated with delirium and was only investigated in residential care. Although various preventive interventions were identified, most studies examined their feasibility rather than their effectiveness in reducing the incidence of delirium.</p> Conclusion <p>Delirium and its risk factors remain insufficiently studied in non-hospital settings. The use of validated diagnostic criteria in community settings is crucial to reduce variation in prevalence estimates, and randomized controlled trials are needed to assess the effectiveness of interventions.</p> Trial registration <p>This scoping review was registered in the Open Science Framework on 9 July 2023 (<a href="https://doi.org/10.17605/OSF.IO/DVYWC">https://doi.org/10.17605/OSF.IO/DVYWC</a>).</p>