Measuring demented patients' 'quality of life' is an important issue in the Netherlands. Due to diminished cognition and other characteristics of dementia, general instruments are not suitable. A conceptual model for quality of life in dementia should guide instrument choice. We used a recently developed model, in which 'well-being' is indicated as the standard for quality of life. Appropriateness of fit in the model is shown of three important instruments developed in the '90s. Eventually, the 'Dementia Quality of Life instrument' (DQoL or D-QoL) of Brod et al., 1999 was selected as exhibiting the best fit. The DQoL measures well-being as a balance of positive and negative aspects. Other instruments consider, for example, either positive or negative aspects or include determinants of well-being, such as the general health condition. In contrast to the other instruments, the DQoL requires only the patient's own opinion. We plan further validation of the DQoL in Dutch demented patients.