The current study compared the predictions of two socio-cultural theories, shifting standards and intergroup bias, to predict sexual double standards that occur in reactions to computer-mediated infidelity. Shifting standards theory (Biernat In The shifting standards model: Implications of stereotype accuracy for social judgment, APA, Washington DC, 1995) suggests that individuals will judge female targets more harshly than male targets, based on culturally ingrained stereotypes regarding sexual behavior. On the contrary, intergroup bias theory (Brewer In Psychol Bull 86:307-324, 1979) predicts that individuals will judge outgroup targets, or members of the opposite sex, more harshly than ingroup targets, or members of the same sex. Participants were shown a hard copy of presumable evidence that extradyadic computer-mediated behavior had occurred, engaged in by one of two members of a couple. The two groups differed only by the sex of the target, the female "Colleen" or the male "Bill". Then participants reported their attitudes toward the target's behavior, resulting distress, and likelihood to terminate the relationship. Results showed support for the intergroup bias theory, suggesting that individuals altered their attitudes toward the behavior based on whether the target was an ingroup or outgroup member. © 2010 Springer Science+Business Media, LLC.