Background: The assessment of psoriasis severity is complex and involves both the physical and psychologic assessment of the individual patient. Objective: We compared the Salford Psoriasis Index and several other tools for assessing psoriasis severity for their abilities to assess both the physical and psychologic effects of psoriasis. Methods: A total of 101 patients (44 women, 57 men) were assessed by means of the Salford Psoriasis Index (SPI), Psoriasis Area and Severity Index (PASI), Self-Administered PASI (SAPASI), Psoriasis Disability Index (PDI), Hospital Anxiety and Depression Scale (HADS), and Illness Perception Questionnaire (IPQ). Results: The “signs” score of SPI (which measures the clinical extent of psoriasis), PASI, and SAPASI correlated well with each other (r = 0.69-0.99; P < .01). They also correlated significantly, but not as strongly, with scores of psoriasis-induced disability, the PDI and SPI “psychosocial disability” score (r = 0.46-0.51; P < .01), but not with general measures of psychologic distress. There was no significant correlation between the historical treatment, “intervention,” score in SPI and either the physical or the psychologic score in the SPI. The PDI and “psychosocial disability” score of SPI correlated well with each other (r = 0.69; P < .01) as well as with the depression and anxiety subscale scores of HADS (r = 0.33 and r = 0.37; P < .01, respectively), the total number of symptoms suffered by the patient (r = 0.38; P < .01), and the belief that stress or worry were associated with psoriasis (r = 0.33; P < .01). Conclusion: Physical scores of psoriasis severity such as PASI, SAPASI, and the “signs” component of SPI give a partial indication of psychosocial disability caused by psoriasis. In many patients, however, the physical score does not reflect psychosocial disability. Patients should be assessed by a more holistic approach, which takes into account both physical and psychologic measurements, such as used in SPI, when assessing the severity of psoriasis. (J Am Acad Dermatol 2001;45:72-6.)