We experimentally study whether individuals adopt negative beliefs about others' intentions to justify egoistic behavior. Our first study compares the beliefs held by players with such an incentive to the beliefs of neutral observers and finds no evidence that individuals engage in “strategic cynicism.” This contrasts with other recent evidence demonstrating that people hold less positive beliefs about others when doing so allows them to act more self-interestedly. We reconcile the discrepancy, using a simple model of belief manipulation and a novel experiment that replicates and extends the earlier findings. Across three datasets, we find no evidence of negatively biased beliefs in absolute terms. However, those with a greater incentive to view others' intentions cynically exhibit relatively less positive beliefs. Our contribution expands our understanding of the psychological forces underlying self-serving belief manipulation, by noting that strategic cynicism may compete with a tendency towards positivity in determining individuals' beliefs.