In 2013, governments across the European Union (EU) gave the European Commission a mandate to negotiate the Transatlantic Trade and Investment Partnership (TTIP) with the United States. Since July 2013, the two sides have held seven rounds of negotiations, but they have not yet reached an agreement. A motivating factor of TTIP is “regulatory convergence”, bringing American and European standards closer together to facilitate trade. One potential obstacle is the subject of genetically modified organisms (GMOs) in the context of food safety regulation. Approximately 70 percent of all processed food in American supermarkets contain GM ingredients, in contrast to the EU where GM food is severely restricted. This talk will review the regulatory differences between the two sides and how different approaches to GMO risk assessment create an obstacle to a TTIP agreement.