The aim of this study was to examine social comparison in illness using a mixed-methods approach that combined inductive exploration of how people used social comparison in this self-help group with a quantitative study of social comparison processes and their relationship to quality of life. The qualitative study involved 15 semi-structured interviews with people with Ménière's disease. Themes from the analysis of the interviews informed the development of the Social Comparison in Illness Scale (SCIS), which was then validated in a questionnaire study, in which participants with Ménière's disease (n = 196) completed the SCIS, the previously validated Identification/Contrast social comparison scale, and the SF-36 health status questionnaire. The qualitative study uncovered a wide range of forms of social comparison, including upward, downward and lateral comparison on illness and coping dimensions, as well as comparing solely for informational purposes. The quantitative study indicated that these varied directions and dimensions of social comparison could be mapped onto five reliable categories that were related to quality of life: upward positive and downward positive comparison, upward negative and downward negative comparison, and comparing for information. These analyses highlight the complexity of socially comparing in chronic illness, but also confirm the validity of the Identification/Contrast model of social comparison in this context.