The degree to which experiential avoidance may represent a functional response class was examined by comparing the perseverance of participants displaying high versus low levels of experiential avoidance, as assessed by the Acceptance and Action Questionnaire (Hayes et al., 2004), during a "psychological biathlon" consisting of 2 challenging tasks that previously had only been studied separately. Consistent with previous research, high avoidant participants were less tolerant of pain and were outperformed by low avoidant participants during a distress-inducing perceptual-motor task. The 2 groups of participants also differed significantly from each other on a composite perseverance measure derived from standard scores on each of the separate tasks, suggesting that experiential avoidance operates as a functional response class. We discuss implications of the findings for the assessment, further investigation, and conceptualization of experiential avoidance as a core process that supports diverse forms of human suffering and dysfunctional behavior. (Contains 4 tables and 1 footnote.)