A vignette methodology was used to investigate the effects of systematically manipulating HIV onset controllability and victim sexual orientation on (a) participant attributions about a victim (i.e., perceptions of victim control, responsibility, and blame); (b) participant emotional reactions (anger and sympathy) toward a victim; and (c) participant helping intentions toward a victim. Weiner's (1980a, 1980b, 1995) attributional helping model was tested to determine whether participant anger and sympathy mediated the onset controllability/helping intentions relationship. A total of 399 undergraduate psychology students completed the survey. Statistically significant effects were found for HIV onset controllability and victim sexual orientation on participant attributions, emotional reactions, and helping intentions. Theoretical and practical implications of the study are addressed.