Wilmette’s sister city is Mona Vale, which is a suburb in northern Sydney, in the state of New South Wales, Australia. Mona Vale is located 28 kilometers north of the Sydney central business district and is the administrative centre of the local government area of Pittwater Council. Mona Vale is also part of the Northern Beaches region.
Mona Vale and New Trier High school participate in an annual student exchange program. Mona Vale and Wilmette both are home to a Baha’i House of Worship, of which there are only seven in the world.