OBJECTIVE: The present study aimed to investigate the impact of Body Mass Index (BMI), duration of illness and severity of illness on quality of life within a sample of individuals in treatment for an eating disorder. In addition this study explored differences in specific areas of quality of life (Psychological, Physical/Cognitive, Work/School and Financial) according to specific eating disorder diagnoses. METHOD: Participants (N = 156) were adults currently receiving treatment for an eating disorder. Eating disorder symptomatology and quality of life were assessed using self-report questionnaires. BMI, duration of illness and eating disorder diagnosis was obtained during a clinical interview. RESULTS: Severity of the eating disorder and BMI were predictors of low quality of life. Duration of illness, contrary to clinical expectations was not a significant predictor of poor quality of life. In terms of differences across diagnostic groups, individuals with a diagnosis of anorexia nervosa in this sample were found to have lower psychological and physical/cognitive quality of life than those with an EDNOS or BN diagnoses.