There has generally been a dearth of good clinical descriptions of grades of disease severity. The aim of this study was to produce reliable and valid descriptions of grades of severity of Atopic Dermatitis (AD). The ADAM (AD Assessment Measure) measure was used to assess AD severity in 171 male and female paediatric patients (mean age = 54 months) at the Royal Children's Hospital in Melbourne, Australia. The assessments were subject to Partial Credit analyses to produce clinically relevant "word pictures" of grades of severity of AD. Patterns of AD were shown to vary according to age, sex and severity. These descriptions will be useful for clinical training and research. Moreover, the approach to validation adopted here has important implications for the future of measurement in medicine.