Gillis is married to Christina Mardsen Gillis, author of Writing on Stone: Scenes from a Maine Island Life.
Academic work
Gillis' early work was largely in social and cultural history. He began as a German historian, moved to British history, and then to age relations, marriage, memory, and the cultures of European and American family life. He later moved on to global history, with an emphasis on cultural geography and environmental history. In 2004 he published Islands of the Mind, on the role played by islands in the economic, political, and social dimensions of Atlantic world and the way the myths, images, and narratives of islands function for mainland cultures. Gillis subsequently began studying the history and geography of coasts and coastal peoples. In his 2012 book The Human Shore: Seacoasts in History, he begins with the first humans to approach the shore, tracing coastal migrations around the world, and discussing the ways that coasts and coastal people have figured in globalization over several centuries. The book concludes with an assessment of the current crisis of coasts when faced with the effects of climate change, treating coasts as an ecotone that encompasses both land and water. The book was published by the University of Chicago Press. Gillis retired from Rutgers University in 2005 and since that time has lived in Berkeley, California while spending summers on Great Gott Island, off Acadia National Park in Maine. There he is involved with the Island Institute, in Rockland, Maine. He has published six books and edited four others.
Academic advising
Gillis was an active and highly respected doctoral adviser, steering eleven students to their PhDs at Rutgers. These former advisees include:
Laura Tabili, Black workers in imperial Britain, 1914-1945
Kelly Boyd, "Wait till I'm a man": Ideals of manliness in British boys' story papers, 1855-1940
Deborah S Cornelius, In search of the nation: The new generation of Hungarian youth in Czechoslovakia, 1925-1931
Tammy Proctor, Gender, generation, and the politics of guiding and scouting in interwar Britain
Benjamin Lammers, A superior kind of English: Jewish ethnicity and English identity in London's East End, 1905-1939
Victoria Smith, Constructing Victoria: The representation of Queen Victoria in England, India, and Canada, 1897-1914
Patrick McDevitt, May the best man win: Sport, masculinity and nationalism in Great Britain and the Empire, 1884-1933
Maritha Rene Burmeister, Popular anatomical museums in nineteenth-century England
Charles Upchurch, '...and every solicitation, persuasion, promise, or threat': The regulation of male same-sex desire in London, 1820 to 1870
Lia Paradis, Return ticket: The Anglo-Sudanese and the negotiation of identity, 1920—1965
Lisa Kazmier, A modern landscape: The British way of death in the age of cremation
