This chapter explores three issues. The first is when the patient is not able to give a reliable rating themselves, so a proxy must be used. Evidence shows proxies overestimate disability and underestimate distress. There may also be a substantial noise element. The second is to assess the self-perception of unpaid care-givers. In a case study, patients and unpaid caregivers had quite similar and low quality of life, but care givers had less disability and found what they did more worthwhile. Proxy and caregiver measures may require slight modifications from patient-reported versions. The third is the use of measures within care homes. There are problems in asking patients with conditions such as dementia to rate themselves. It is easier to ask staff to rate patients in terms of health status and their own perceptions of working there.