Laboratory evidence about whether students’ evaluations of teaching (SETs) are valid is lacking. Results from three (3) independent studies strongly confirm that "professors" who were generous with their grades were rewarded for their favor with higher SETs, while professors who were frugal were punished with lower SETs (Study 1, d = 1.51; Study 2, d = 1.59; Study 3, partial η2 = .26). This result was found even when the feedback was manipulated to be more or less insulting (Study 3). Consistent with laboratory findings on direct aggression, results also indicated that, when participants were given a poorer feedback, higher self-esteem (Study 1 and Study 2) and higher narcissism (Study 1) were associated with them giving lower (more aggressive) evaluations of the "professor." Moreover, consistent with findings on self-serving biases, participants higher in self-esteem who were in the positive grade/feedback condition exhibited a self-enhancing bias by giving their "professor" higher evaluations (Study 1 and Study 2). The aforementioned relationships were not moderated by the professor's sex or rank (teaching assistant vs.professor). Results provide evidence that (1) students do aggress against professors through poor teaching evaluations, (2) threatened egotism among individuals with high self-esteem is associated with more aggression, especially when coupled with high narcissism, and (3) self-enhancing biases are robust among those with high self-esteem. Aggr. Behav. 39:71-84, 2013. © 2012 Wiley Periodicals, Inc.