ESY Services are Special Education and related services provided to students with Disabilities beyond the regular 180 day school year:

in MA the legal standard is 603 CMR 28.05(4)(d) which states:

"An extended year program may be identified if the student has demonstrated or is likely to demonstrate substantial regression in his or her learning skills and/or substantial difficulty in relearning such skills if an extended program is not provided."

Important facts about ESY click here.