We propose and demonstrate in 11 studies, including more than 4,700 observations, that the persuasiveness of a target message can be increased by the inclusion of a reactance decoy. A reactance decoy is a persuasive message presented before the target message and includes an attitude measurement toward the decoy object. The effect can be explained with reactance theory: The decoy message is presented to create reactance and expressing their attitude toward the decoy object gives participants the opportunity to vent, that is, to reestablish their threatened freedom. This reduces reactance toward the subsequently presented target message, positively influences participants' willingness to buy the target object (Studies 1, 4a and 4b, 7, and 8), their attitudes toward it (4a and 4b, 5, 7, and 8), their willingness to pay (Study 7), as well as behavioral measures such as time spent looking at the target object description (Study 7) and paying money to enter a raffle for the chance to win the target object (Studies 5 and 6). Moreover, forewarning participants of the persuasive intent of a subsequent message produced greater reactance, which was then vented on the decoy, and in turn increased the valuation of the target object (Study 1). By interchanging the products used as decoy or target objects, we also demonstrate experimentally that the reactance decoy effect occurs independently of the concrete stimuli being used (Study 3). In sum, the reactance decoy effect is a new theoretical framework that also bears important practical applications for many areas of social influence. (PsycInfo Database Record (c) 2020 APA, all rights reserved).