Background: The problem of fatigue in Rheumatoid Arthritis (RA) was brought to the attention of healthcare professionals by patients at an international meeting in 2002. Since then research has established that fatigue is an important problem for patients. In order for effective interventions to be developed reliable and robust tools are required to measure RA fatigue. This research first set out to evaluate tools to measure RA fatigue in UK patients, but found there were none that captured the fatigue experienced by RA patients. It was therefore necessary that new scales should be developed to address this issue. Identifying the patient perspective: First, interview transcripts of patients describing their fatigue experience (n=15) were explored to identify the language that patients used to express their fatigue and its' consequences. These data were utilised to identify 12 concepts of fatigue: Cognition, Coping, Duration, Emotion, Energy, Frequency, Impact, Planning, Quality of Life, Relationships, Sleep, Social life, (Study 1, Chapter 2). Focus groups: To ensure data generalisability and robustness three focus groups were conducted to further explore the issues identified in Study 1. In addition, the focus group members developed the wording for visual analogue scales and numerical rating scales to measure fatigue severity, effect of fatigue and ability to cope with fatigue (Chapter 3). Scale design: Using these data and sources from the literature a preliminary multi-item questionnaire and a set of short scales to measure fatigue were developed (Chapter 4). To ensure that the scales were understood by patients in the way intended a "think aloud" study was conducted, which led to changes in wording and layout of the scales (Chapter 5). Scale validation: Quantitative research was employed to conduct validation of the scales. The short scales were found to be valid and able to measure the concepts of severity, effect and ability to cope with fatigue (Chapter 6). The multi-item questionnaire contained four separate dimensions of fatigue, namely Cognition, Emotion, Living and Physical (Chapter 7). Preliminary exploration of the data found differences in fatigue experience between genders and within genders (Chapter 8). Conclusion: These scales will allow the individual experience of RA fatigue to be measured and facilitate development of individually tailored fatigue interventions.