The “504” in “504 plan” refers to Section 504 of the Rehabilitation Act and the Americans with Disabilities Act. These references specify that no one with a disability can be excluded from participating in federally funded programs or activities, including elementary, secondary or postsecondary schooling. The word disability in this context refers to a “physical or mental impairment with substantially limits one or more major life activities.” This can include physical impairments; illnesses or injuries; communicable diseases; chronic conditions like asthma, allergies and diabetes; and learning problems.
A 504 plan spells out the modifications and accommodations that will be needed for these students to have an opportunity to perform at the same level as their peers, and might include such things as wheelchair ramps, blood sugar monitoring, an extra set of textbooks, a peanut-free lunch environment, home instruction, or a tape recorder or keyboard for taking notes.
Source: Mauro, Terri (2015). What Is A 504 Plan. Specialchildren.about.com. Retrieved from http://specialchildren.about.com/od/504s/f/504faq1.htm