The Mercer County Special Services School District (MCSSSD) is a special education public school district headquartered in Hamilton Township, in Mercer County, in the U.S. state of New Jersey, whose schools offer educational and therapeutic services for students of elementary and high school age from across the county who have emotional of physical disabilities that cannot be addressed by their sending districts. The district was created in November 1977.

As of the 2022–23 school year, the district, comprised of four schools, had an enrollment of 126 students and 75.0 classroom teachers (on an FTE basis), for a student–teacher ratio of 1.7:1.

The superintendent for the district is also the superintendent for the Mercer County Technical Schools.

Schools in the district (with 2018-19 enrollment data from the National Center for Education Statistics) are:

• Joseph F. Cappello School (96; PreK-6)
  • Clara Bigos, principal
• Mercer Elementary School (191; 3-8)
  • Carline Mirthil, principal

High school

• Mercer High School (271; 9-12)
  • Brian Kozakowski, principal
• New Jersey Regional Day School at Hamilton (1; 9-12)
  • Brian Kozakowski, principal

Core members of the district's administration are:

• Matthew C. Carey, superintendent
• Deborah Donnelly, business administrator and board secretary

• Official website