Background: Performing basic activities of daily living (ADLs) is one of the major difficulties encountered in dementia, which can have considerable negative impacts on the quality of life (QoL) of people with dementia (PwD). However, the extent to which basic ADL performance deteriorates across mild, moderate, and severe dementia is little examined and its impact, together with depression and neuropsychiatric behavior, upon QoL, is of considerable relevance across European countries. Methods: Data were drawn from people living in the community who were participants in a large-scale European study on transition from community living to care homes of PwD. PwD completed measures on cognitive functioning and QoL, and informal carers reported upon QoL, depressive symptomatology, psychopathology, and functional ability of the PwD. Results: ADL performance deteriorated differently for each activity. In particular, toileting, transfer, and feeding remained relatively intact throughout, whereas performance on bathing and dressing deteriorated to a greater extent from mild to severe dementia. It appears that continence was not affected by the stage of dementia with similar levels of impairment. Basic ADL performance impacted to different degrees on QoL across dementia stages and countries. Conclusions: Interventions aimed at maintaining independence or QoL need to target different ADLs across different dementia stages and perhaps also tailor interventions to the context of different countries. Findings contribute to the development of non-pharmaceutical interventions and governmental pledges to promote independence in dementia.