OBJECTIVE: To develop a scalp dermatitis-specific quality-of-life instrument. METHODS: Based on the results of directed focus sessions with 8 patients with scalp psoriasis or seborrheic dermatitis, we conceptualized 3 major constructs that explain the way scalp dermatoses affect patient quality of life: symptoms, functioning, and emotions. We constructed a 23-item instrument, Scalpdex, and tested its reliability, responsiveness, and validity. RESULTS: Fifty-two dermatology patients completed the study. We demonstrated construct validity by confirming that the factors derived by principal axes factor analyses with orthogonal rotation correlated to our hypothesized scales (r = 0.76-0.84) and that differences in symptom, functioning, and emotion scores differed among the varying levels of self-reported scalp severity more than would be expected by chance (P<.05 by analysis of variance). The instrument demonstrated reliability with internal consistency (Cronbach alpha, 0.62-0.80) and reproducibility (intraclass correlation coefficient, 0.90-0.97). The quality-of-life scores changed in the expected direction in our test for responsiveness (P