Power posing, the idea that adopting expansive postures causes people to feel more powerful, has received significant attention in recent years, with some research suggesting that the positive benefits of power posing may extend to the workplace through its effect on confidence, performance, and the ability to endure stressful situations (Carney, Cuddy, & Yap, 2010). However, research examining the causal mechanisms underlying the effects of power posing is sparse, and such research may be particularly impactful given recent criticism of power posing effects (Ranehill et al., 2010; Simmons & Simonsohn, 2015). The current study employs an experimental design in a multinational negotiation setting to test whether power posing replicates across country contexts and to particularly examine whether power posing effects are driven by the expansive posture itself or by people's belief that that the posture will have an impact. Results, theoretical and practical implications, limitations, and directions for future research are discussed.