Background: The Dermatology-Specific Quality of Life (DSQL) instrument is a new tool to quantify the effects of skin disease on physical discomfort and symptoms, psychologic well-being, social functioning, self-care activities, performance at work or school, and self-perceptions. Objective: Our purpose was to describe the reliability and validity of the DSQL in two disease cohorts comprising patients with contact dermatitis and acne vulgaris. Methods: Reliability was assessed from the internal consistency of the items, and correlations were made between DSQL scores from a 3- to 7-day retest. Validity was assessed from correlations of DSQL scales with global ratings of bothersome symptoms and perceived severity and by discrimination of clinically defined severity groups. Results: The DSQL scales had high internal consistency (0.70 to > 0.90) and test-retest reliability ( r = 0.81 to 0.89), and were moderately to highly correlated with patient global ratings of symptom distress ( r = 0.25 to 0.67) and overall disease severity ( r = 0.19 to 0.54). Patients rated with severe contact dermatitis or acne scarring had higher DSQL scores than those with less severe skin disease. Factor analyses found separate dimensions of physical, emotional, and social functioning involvement from skin disease. Conclusion: The DSQL provides valid and reliable assessments of quality of life impacts associated with acne and contact dermatitis. (J Am Acad Dermatol 1997; 37:41–50).