Publishes 'Theory of Games and Economic Behavior' with Oskar Morgenstern, a landmark book that establishes game theory as a formal mathematical discipline and applies it to economic analysis. The book introduced the concept of utility function and explored cooperative and noncooperative games. This is his most well known publication.

Continues to refine and expand game theory, exploring its applications to various economic problems, including bargaining, competition, and market equilibrium. He contributed to the development of linear programming.

Applies game theory concepts to Cold War strategy, advising the US government on nuclear deterrence and arms control. His work on mutually assured destruction (MAD) was impactful.