Following the same format as their critically acclaimed companion work about Long Island's North Shore families, "Long Island's Prominent South Families: Their Estates and Their Country Homes in the Towns of Babylon and Islip" documents 456 estate owners in a modified "Who's Who" format. Included are 290 photographs of the estates, biographical data on the estate owners and their families, locations of estates using current street references and village designations, estate names, architects, architectural styles, dates of construction, landscape architects, subsequent owners, location of archival photographs of the estates, and information as to whether mansions are still extant, and, if not, the dates of demolition. Cross-referenced in the second-section appendices are estate names, village locations of estates, as well as, architectural and landscape commissions. The civic activity and occupation appendices document the contribution of Long Islanders, including statesmen, intelligence agents, financiers, writers, and inventors.
Maiden names, rehabilitative secondary uses of estates including golf courses which were formerly private estates, a general bibliography of the "Gilded Age," and a bibliography specific to individual estate owners, with the location of personal papers, have also been included.