This article provides an introduction to the theoretical underpinnings of expected utility and game theory approaches in IR studies. It goes on to explore their application to a specific research subject, international bargaining on Iran’s nuclear program. In this application, the article presents forecasts about Iran’s nuclear program using a game theoretic, bounded rationality model called the expected utility model (Bueno de Mesquita 2002). Three analyses were made in December 2005, September 2006 and March 2007. All three forecasts appear to be in line with real-life developments regarding the issue. The results show that Iran has been losing international support since the analyses started, and the last forecast suggests a pro-US position supported by all major international actors. Also, all three analyses suggest that Russian and Chinese support is vital to curb the Iranian nuclear program.