The Crocker-McMillin Mansion is a historic house in Mahwah, New Jersey. It was built between 1903 and 1907 on the Darling estate for businessman George Crocker. After Crocker died in 1909, the banker Emerson McMillin lived in the 75-room, three-story residence until his death in 1922. From 1927 to 1984, the mansion was occupied by the Crocker-McMillin Mansion-Immaculate Conception Seminary. The property, located at 675 Ramapo Valley Road in Mahwah, is one of New Jersey's historical landmarks. It was listed on the National Register of Historic Places in 1997.

Mahwah is the northernmost and largest municipality by geographic area in Bergen County, in the U.S. state of New Jersey. As of the 2020 United States census, the township's population was 25,487, a decrease of 403 (−1.6%) from the 2010 census count of 25,890, which in turn reflected an increase of 1,828 (+7.6%) from the 24,062 counted in the 2000 census. The name "Mahwah" is derived from the Lenape language word "mawewi" which means "Meeting Place" or "Place Where Paths Meet".