Excerpt from About.com: (click for entire article)
What is ESY?
Some students with special needs are in jeopardy of not being able to retain the skills they have learned during the school year unless given addition support throughout the summer. Those students eligible for ESY will receive an individualized program to support their learning and retention of skill throughout the summer holidays.
What does IDEA say about ESY?
Under (34 CFR Part 300) in IDEA Regulations (not the Act): 'Extended school year services must be provided only if a child's IEP team determines, on an individual basis, in accordance with 300.340-300.350, that the services are necessary for the provision of FAPE to the child.'
'The term extended school year services means special education and relatedservices that—
(1) Are provided to a child with a disability—
(i) Beyond the normal school year of the public agency;
(ii) In accordance with the child's IEP; and
(iii) At no cost to the parents of the child; and
(2) Meet the standards of the SEA'