WRMA was awarded a contract by the USDA’s Food and Nutrition Service to produce fiscal year (FY) 2013 estimates of the rates and amounts of overcharging and undercharging by WIC vendors. The WRMA team aged the 2012 WIC Vendor Management System (WVMS) data to generate FY 2013 national estimates of the amounts of overcharges and undercharges, and the numbers of vendors who overcharged or undercharged. These national estimates used methods consistent with the methods used since FY 2005 and newly developed methods. In addition, the WRMA team developed growth rates based on FYs 2012 and 2013 annual data and applied them to 2012 WVMS estimates. Finally, the WRMA team developed new Bayesian models to produce estimates. The team used the same three approaches to estimate national overcharges and undercharges for FYs 2006-2012 based on the 2005 WVMS. The team also generated overcharge and undercharge estimates by WIC transaction type (i.e., food instrument, cash value voucher, electronic benefit transfer, and cash benefit voucher).