[Clin Psychol Sci Prac 17: 48–51, 2010]
Researchers and practitioners have long debated the meaning and measurement of clinical significance. Shearer-Underhill and Marker (2010) offer a valuable contribution to this discussion by drawing the psychotherapy research community’s attention to an additional statistical method for measuring clinical significance—the number needed to treat. After a decrease in publication rates in the last 5 years on methods for measuring clinical significance, the article by Shearer-Underhill and Marker represents a renewed interest in the construct of clinical significance of treatment outcome results. This commentary discusses the importance of the article by elaborating on the theoretical and methodological issues that cut across measures of clinical significance. Strengths and weaknesses of specific statistical methods are reviewed and a call is made for continued pursuit of conceptual clarity and methodological rigor for measures of clinical significance.