Information can change: science advances, newspapers retract claims, and reccomendations shift. Successfully navigating the world requires updating and changing beliefs, a process that is sensitive to a person's motivation to change their beliefs as well as the credibility of the source providing the new information. Here, we report three studies that consistently identify an additional factor influencing belief revision. Specifically, we document an asymmetry in belief revision: people are better able to believe in a claim once thought to be false, as opposed to unbelieving something once believed to be true. We discuss how this finding integrates and extends prior research on social and cognitive contributions to belief revisions. This work has implications for understanding the widespread prevalence and persistence of false beliefs in contemporary societies.