Tanzania is largely an agriculture-based economy. This sector accounts for over three-quarters of national employment, and approximately 25 percent of gross domestic product (GDP). The national agricultural input voucher scheme (NAIVS) is a market smart input subsidy program designed in response to the sharp rise in global grain and fertilizer prices in 2007 and 2008.This report summarizes an overview of the program, and the results of two major impact surveys independently conducted in late 2010 and late 2012.