When people feel prejudice toward a group, they can justify their prejudice by perceiving the group as threatening. Three experiments tested the hypothesis that prejudice causes threat perception, using affective conditioning to create new prejudice toward unfamiliar groups. The experimentally created prejudice increased threat perception (Experiments 1–3), except when threat information was inconsistent with conditioned affect (Experiment 3). Consistency of affect and threat information is necessary in order for threat to be a plausible justification of prejudice. Mere prejudice can cause perception of threat in the absence of information about the group; this finding suggests threats are not necessarily inherent to the characteristics of the group. Threat perception can be used as a way to explain the experience of prejudice, rather than forming the source of the prejudice itself.