Despite sustained efforts made by developing countries and the international community hunger and malnutrition continue to be major challenges faced by millions of individuals and communities. While domestic policies and investments in food insecure countries will be essential in addressing the needs and gaps that exist, policies from outside their borders also play an important role. Given the importance of OECD countries in world trade, this study seeks to understand the spillover effect of their domestic non-aid policies on the food security in developing countries with a focus on Tanzania. We consider various OECD countries policies such as domestic supports to agriculture, non-tariffs measures and foreign direct investment policies. Using a set of qualitative and quantitative methods and sectoral studies we found that, historically, OECD countries policies have had sizable negative effects on Tanzanian agriculture and food security. The direction and magnitude of the effects varies across sectors and households. We also found that in recent years, the OECD has been actively engaged in efforts to promote the coherence of its policies to ensure that they are mutually supportive of development goals in the developing world.