About one third of the Vietnamese population lives below the poverty line, and 85% of the poor live in rural areas. The primary expenditure instrument used by the Government of Vietnam to improve rural incomes has been subsidized irrigation investments. Irrigation accounts for about half of all public expenditures in the agricultural sector, and three-quarters of all capital investments. The primary question posed by this study is: how effective are public irrigation expenditures in increasing rural incomes, particularly for the poor?