The ability of the Social Phobia and Anxiety Inventory (SPAI) to measure change as a function of treatment for social phobia was assessed. In addition to determining treatment sensitivity of the SPAI, changes over the course of treatment were examined to determine if they were reliable and clinically significant. The results indicated that although a number of measures showed statistically significant change, only on the SPAI was that change reliable and clinically significant. The use of outcome measures that are reliable and clinically significant for social phobia as well as other disorders is discussed.