Through interviews with judges and victim advocates, courtroom observations, and rhetorical analyses of victims' reactions to proposed sentences, the authors examine the features that judges and advocates think make victims' arguments persuasive. The authors conclude that this genre, recently imposed upon the court, functions as a mediating device through which advocates push for collective change, particularly for judicial acceptance of personal and emotional appeals. This study understands genres as responsive to changes within the activity systems in which they work and extends knowledge about genres that function as advocacy tools within internal institutional systems. (Contains 1 table, 1 figure, and 5 notes.)