The present study was designed to test the psychometric properties of the RAQoL, a rheumatoid arthritis (RA)-specific quality of life (QoL) instrument. All stages of the development were conducted simultaneously in The Netherlands and the UK. The content of the draft measure was derived from qualitative interviews with RA patients in both countries. The final version of the RAQoL has 30 items with a 'yes'/'no' response format and takes approximately 6 min to complete. Both language versions have high internal consistency and test-retest reliability (> 0.9), and good sensitivity to discriminate between groups with various disease activity and severity. Given the excellent psychometric properties of the new instrument, it will prove to be a valuable tool for assessing quality of life in clinical trials and for monitoring patients in routine clinical practice.