This article presents two studies examining the effects of disclosing online native advertising (i.e., sponsored content in blogs) on people’s brand attitude and purchase intentions. To investigate the mechanisms underlying these effects, we integrated resistance theories with the persuasion knowledge model. We theorize that disclosures activate people’s persuasion knowledge, which in turn evokes resistance strategies that people use to cope with the persuasion attempt made in the blog. We tested our predications with two experiments (N = 118 and N = 134). We found that participants indeed activated persuasion knowledge in response to disclosures, after which they used both cognitive (counterarguing) and affective (negative affect) resistance strategies to decrease persuasion. The obtained insights do not only advance our theoretical understanding of how disclosures of sponsored blogs affect persuasion but also provide valuable insights for legislators, advertisers, and bloggers.