Section 504 of the Rehabilitation Act requires that accomodations be made for individuals with disabilities in institutions that receive federal funds. Students that have disabilties that "limit one or more of life's major activities," but are not eligible for special education services under state and local school systems' criteria for eligibility, must still have accomodations made for them under this act. These accomodations must be made in the general education classrooms. The students that are not found eligible for sped services, but are given accomodations under Section 504, have what is called a 504 Plan.
Your local school system or state department of education should be able to give you more information about the plans and how they work.
Hope this helps!