This study focuses on the effect of internationalization on the wider society. The study analyses the results of a session on terrorism and media, where participants were the wider public in the United Kingdom. An experimental design with random group assignment was conducted where internationalization was operationalized by the training either being international, where a U.S. trainer co-conducted the intervention group session, or national, where a U.K. trainer co-conducted the control group session. Both groups were matched for age, education, and gender. While both groups did not significantly differ regarding a core personality trait--that is, openness--as well as the learning outcomes prior to the training, they differed significantly post training. Training on terrorism showed consistent learning effects for both groups, but was far greater in the presence of the U.S. co-teacher and these effects were long-term. Consistent with predictions, the presence of an international trainer produced significantly larger effects when compared with when the trainer was not international.