Many of the ‘new’ agricultural input subsidy programs (ISPs) in sub-Saharan Africa list raising farm incomes and reducing rural poverty among their objectives, but are ISPs achieving these objectives? We use data from two nationally-representative surveys of smallholder farm households in Zambia to estimate the effects of an increase in ISP fertilizer on household incomes, poverty severity, and the probability of household income falling below the US$2 and US$1.25/capita/day poverty lines. Results suggest that although ISP fertilizer raises smallholder incomes, the increase is not large or widely distributed enough to substantively reduce the probability or severity of poverty.