Retailers increasingly require suppliers to certify for food safety standards. Third party certification bodies audit manufacturing sites to determine compliance with a standard. We use panel data on U.S. manufacturing sites certified for the British Retail Consortium global standard food safety program to identify determinants of certification audit grades. We find that firms with more resources obtain higher grades. Also grades increase with experience which likely indicates that the certification process improves food safety practices. Investigating the relationship between audit grades and the degree of competition between third party certification bodies in the vicinity of a manufacturing site, we find that higher competition is associated with higher audit grades.