This investigation examined the boundaries of inoculation theory by examining how inoculation can be applied to conspiracy theory propaganda as well as inoculation itself (called metainoculation). A 3-phase experiment with 312 participants compared 3 main groups: no-treatment control, inoculation, and metainoculation. Research questions explored how inoculation and metainoculation effects differ based on the argument structure of inoculation messages (fact- vs. logic-based). The attack message was a 40-minute chapter from the 9/11 Truth conspiracy theory film, Loose Change: Final Cut. The results indicated that both the inoculation treatments induced more resistance than the control message, with the fact-based treatment being the most effective. The results also revealed that metainoculation treatments reduced the efficacy of the inoculation treatments.