Actuarial Science. NCES CIP Code 52.1304

Computer Science: NCES CIP Codes 11 .xxxx (except Data

Entry/Microcomputer Applications, NCES CIP Codes 11.06xx)

Engineering: NCES CIP Codes 14.xxxx

Engineering Technologies: NCES CIP Codes 15.xxxx

Biological and Biomedical Sciences: NCES CIP Codes 26.xxxx

Mathematics and Statistics: NCES CIP Codes 27.xxxx

Military Technologies: NCES CIP Codes 29.xxxx

Physical Sciences: NCES CIP Codes 40.xxxx

Science Technologies: NCES CIP Codes 41.xxxx

Medical Scientist (MS, PhD): NCES CIP Code 51.1401

STEM Designated Degree Program List is based on the US Departmen of Education's "Classification of Instructional Program" (CIP) 2000 report which you can find online at 

http://nces.ed.gov/pubs2002/2002165.pdf 

See the list and find if your major falls under STEM or not.