In the past decade, the world has witnessed a remarkable explosion in international support for improving health in low and middle income countries. In the absense of a comprehensive resource tracking system that monitors investments from public and private global health actors, we know relatively little about the total magnitude of these investments, how they have changed over time, and distribution across different diseases. Futhermore, the question of whether these international resources constitute additional investments in the health sectors of the recipient countries or are merely substituting domestic government expenditure, which is vital for assessing the effectiveness of aid, has yet to be analyzed in detail. The papers in this session explore both the nature of international development assistance for health and their impact on national health expenditure.