Greathorse posted the link to the USDA website that explains the National Organic Program in laymens' terms.
If you want to get down to the nitty-gritty of it, the actual federal regulations, it is in Title 7 of the Code of Federal Regulations:
http://tinyurl.com/22nf673
If you want to get down to the nitty-gritty of it, the actual federal regulations, it is in Title 7 of the Code of Federal Regulations:
http://tinyurl.com/22nf673