Although the effectiveness of inoculation as a strategy for promoting resistance to attitude change is fairly well established, the potential of inoculation messages to offer cross-protection for related, but untreated, attitudes warrants additional attention from scholars. The reported study tested the “blanket of protection” conferred by inoculation. Participants (N = 118) were randomly assigned to read an inoculation message addressing a target topic and subsequently had their attitudes toward three related, but untreated, topics attacked. The results offer some evidence that inoculation messages can confer cross-protection for related attitudes. Participants in the inoculation condition reported greater perceptions of threat, greater counterarguing, and less attitude change in response to attacks than participants in the control condition for two of the three untreated topics. Counterarguing in response to attacks on untreated attitudes appears to be primarily responsible for cross-protection.