Islander Middle School is the only public middle school on Mercer Island and is host to sixth, seventh, and eighth grade students. IMS is located on the south end of the island at 7447 84th Ave. SE.

Co-principals Mary Jo Budzius and Aaron Miller, along with associate principal Tara Stone, lead approximately 75 staff members and 1,000 students. IMS utilizes district-adopted curriculum as the foundation for its core classes as well as offering a variety of engaging learning electives.