Investment in one country can have far-reaching impacts on another country. Such a spillover effect will be particularly strong for a country with a geographical proximity and fully developed domestic input markets. This brief estimates the crossover spillover benefits of a proposed border investment program in the Inner Mongolia Autonomous Region of the People’s Republic of China, most notably for a close neighbor, Mongolia. This analysis looks at the impacts of the investment program on Mongolia as an example of how the costs and benefits of an investment can be distributed across neighboring countries. This study uses a logically consistent framework showing causal links between investment activities and outputs, and between outputs and outcomes, based on the multiregional input–output tables developed by the Asian Development Bank, to evaluate the estimated net economic gains from the program and to measure the cross-border distribution of benefits. The results of the exercise suggest that the induced output growth could reach 5% and create 33,000 jobs, but only if Mongolia fully develops its input markets—for both labor and goods.