Excerpts from report: Mathematica Policy Research conducted the SNAP Food Security (SNAPFS) survey for FNS between October 2011 and September 2012, to assess the effect of SNAP participation on food security and food spending in the post-ARRA environment of higher SNAP allotments. SNAPFS was the largest survey of food security and food spending among SNAP participants to date, with 9,811 households interviewed in 30 States. This report presents the evaluation findings, which are based on a quasi-experimental design intended to minimize selection bias by comparing information collected from SNAP households within days of entering the program to information obtained after about six months of participation to control for factors unrelated to SNAP. The main objectives of the study were to: • Assess how household food security and food expenditures vary with SNAP participation • Examine how the relationships between SNAP and food security and between SNAP and food expenditures vary by key household characteristics and circumstances • Examine in more depth what factors may distinguish between food secure and food insecure SNAP households with children. This report contains the research findings for the first and second objectives. The third objective was based on a qualitative component of the study and was addressed in a separate report. The findings provide strong evidence that SNAP is associated with an improvement in food security. This evidence suggests SNAP is accomplishing one of its main goals, that of reducing food insecurity among low-income households.