The Cora Hartshorn Arboretum and Bird Sanctuary (16.5 acres), also known as the Hartshorn Arboretum, is an arboretum and bird sanctuary located at 324 Forest Drive South, in the Short Hills section of Millburn, in Essex County, New Jersey, United States.

The arboretum began when the 16.5 acres of land was gifted to Cora Hartshorn in 1923 by Stewart Hartshorn on undeveloped woodland of oaks, tulip trees, dogwood, and beech.

The original part of the building, also known as the Stone House, was built in 1933 for Cora.

Membership dues provide crucial support for education programs and maintenance of the woodlands.

The CHA offers a variety of programs and events for children, families, and adults.