The article contributes to the research on older people's mental illness through its focus on how needs assessors conceive mental illness amongst older people and their strategies for dealing with mental illness within existing organisational frameworks. The contribution is based on an empirical study of the needs assessment in eldercare in Sweden. The article aims to explore needs assessors' conceptions of mental illness amongst older people in relation to intertwining processes of normalisation and organisational and legal constraints. The normalisation principle (NP) proposes that individuals with a disability should have access to the same living conditions as ?others?. The NP can be described as a strategy that highlights equal rights for individuals regardless of their life situation. The main findings are that mental illness is defined by needs assessors on a spectrum of diagnoses from schizophrenia and borderline personality disorder to anxiety and depression. The successful normalisation of mental illness is linked to structural context, attitudes to older people's mental illnesses and ageing, the practise established on a unit and whether needs assessors reproduce ageism or challenge it through the NP by attempting to secure the rights of older people.