This study focuses on the assessment of cognitive functioning in geriatric patients. Nurses in geriatric hospital wards pointed out that assessment of cognitive functioning was not standardised or evidence based, what was felt as unprofessional. In a review of the literature Dutch observation scales for cognitive functioning were identified. However these scales had questionable validity and reliability or were not developed for the purpose of assessing observation. Subsequently, on seven geriatric departments a survey was carried out to find out why nurses want to assess cognitive functioning. This survey revealed that these observations contribute to the diagnosis of dementia and that cognitive functioning determines nursing interventions of choice. Starting from these results, the development of an observation scale for nurses was taken on.