Theatrical trends, schools or movements are cultural groupings that fill a central function when considering theatre histories. In many cases, specific critics play a major role in categorizing, defining and characterizing new trends or movements. This article examines the critical phenomenon of defining a trend, concentrating in particular on those critical means employed in constructing a new theatrical trend, school or movement that serve to promote a new type of drama associated with several playwrights. I illustrate these means and how the critics employ them by focusing on two case studies: Martin Esslin's The Theatre of the Absurd (1961) and Aleks Sierz' In-Yer-Face Theatre (2001). Examining the means employed by the two critics serves here not only to map those means that are essential for such a grouping, but also to illustrate how they manifest the critics' practice of claiming authority. Additionally, I relate the differences between the two studies, primarily with respect to the particular phase of the theatrical development (the new type of drama) at the time each study was written, and, consequently, to each author's specific critical intentions.