Section 504 of the Rehabilitation Act of 1973 prohibits discrimination on the basis of disability in programs or activities that receive federal financial assistance from the U.S. Department of Education. 

Resources

The Ultimate Section 504 Accommodations Toolkit by David Bateman, PH.D.

504 Protections for Students with Anxiety Disorders- Office of Civil Rights

Comparison of IDEA, Section 504, and ADA