The Stirling Eating Disorder Scales (SEDS) are widely used in clinical practice, however evidence regarding the internal consistency and validity of the measure is limited. The aim of this study was to investigate the psychometric properties of the SEDS in a mixed eating disorder population. The SEDS and the Eating Disorder Examination (EDE) were administered to 241 consecutive patients attending an adult out-patient eating disorder service in the UK. The internal consistency of the overall SEDS was good, but there was variation in the internal consistency of the individual subscales. There were differences across diagnosis for all SEDS subscales, and some significant correlations were found between the EDE and SEDS subscales. It was not possible to replicate the derivation of the original SEDS subscales using a principal components analysis (PCA); further analysis was conducted on the new subscales that were identified. It is suggested that information obtained from the administration of the SEDS should be interpreted with caution, and also that further exploration of the psychometric properties of the SEDS is warranted.