Pain is common and often more complex to assess among nursing homes residents with cognitive impairments. Thus, more research is needed of different pain assessment methods in elderly care and how these assessments outcomes are related to quality of life, as there mostly should be a negative relationship. There is a risk that pain are under diagnosed among persons with cognitive impairment.The aim was to describe and compare pain prevalence among nursing home residents (1) using different pain assessment methods (2) in relation to cognitive status and to (3) examine associations between pain and quality of life or well‐being.A cross‐sectional correlational design was used, participants were 213 nursing home residents and data were collected through interviews using standardised protocols. Instrument used were Katz index of ADL, Mini‐Mental‐State‐Examination, Quality of Life in Late‐Stage Dementia scale, WHO‐5 well‐being index, Numeric Rating Scale and Doloplus‐2 scale.The results showed high pain prevalence, but no significant difference based on cognitive level. Pain classification at the individual level varied somewhat when different instruments are used. The results indicated that use of a single‐item proxy‐measure for pain tends to show higher pain prevalence and was not statistically significant related to quality of life. The relationship with quality of life was statistically significant when self‐rated pain instruments or multi‐component observation were used.The study shows that it is difficult to estimate pain in residents living at nursing homes and that it continues to be a challenge to solve. Self‐rated pain should be used primarily to assess pain, and a multi‐component observation scale for pain should be used when residents are cognitively impaired. Both self‐rated pain and multi‐component observation also support the well‐known link between pain and quality of life. Single‐item proxy assessments should only be used in exceptional cases.