The Inner Sydney Montessori School (abbreviated as ISMS) is a dual-campus independent nonsectarian Montessori coeducational early learning and primary day school, with campuses located in Balmain and Lilyfield, inner-western suburbs of Sydney, New South Wales, Australia.

The school was founded in Annandale in 1981.

• List of non-government schools in New South Wales
• List of Montessori schools

• School website