Elevated anxiety vulnerability is associated with a tendency to interpret ambiguous stimuli as threatening, but the causal basis of this relationship has not been established. Recently, procedures have been developed to systematically manipulate interpretive bias, but the impact of such manipulation on anxiety reactivity to a subsequent stressor has not yet been examined. In the present study, training procedures were used to induce interpretive biases favoring the threatening or nonthreatening meanings of ambiguous information in a sample of 48 undergraduate students. Following this interpretive training, participants' emotional reactions to a stressful video were assessed. The finding that the manipulation of interpretive bias modified emotional reactivity supports the hypothesis that interpretive bias can indeed play a causal role in anxiety vulnerability.