The De Jong family papers date from 1852-2011 and measure 9 linear feet. They are organized into nine series: Jan (John) and Trijntje (Katherine) De Jong; Jeanette De Jong; Henry and Lorraine De Jong; Bernard and Winifred De Jong; Eunice Florence De Jong; Correspondence of Katherine, Eunice, and Jeanette De Jong; Correspondence of Eunice and Jeanette De Jong; Artifacts; and Audiovisual.

The Jan (John) and Trijntje (Katherine) De Jong series dates from 1915-1996 and includes material on their son Frederick (Fritz) De Jong, including his high school papers and condolence cards sent to the family after his death in 1942. The series also includes condolences sent after John and Katherine's own deaths. Correspondence from John and Katherine's grandchildren (principally Mary and John, as well as Marc, Linda, and Karen) describes the children's daily school life, sometimes accompanied by a performance program or school document. Letters from son Bernard offer comfort following Frederick's death, and telegrams from son Henry chart his movements as an army private. Photographs and other memorabilia complete the series.

The Jeanette De Jong series dates from 1979-2004 and includes cards and correspondence from Jeanette De Jong's family, the program from her funeral (as well as an audiotape of the funeral), and photographs.

The Henry and Lorraine De Jong series dates from 1852-2007 and includes correspondence, yearbooks, scrapbooks, diaries, photographs, and newspaper clippings. While Henry De Jong is the focus of a few of the documents, this series primarily consists of material from Lorraine Schol De Jong. Her scrapbooks chronicle her education as a young singer and her eventual work as choir director for Sheldon High School, as well as her later work teaching refugees from Laos. Diaries record her daily life with Henry De Jong, including weather, household chores, her mother's health, and her reflections on her marriage. Completing the series is an album of Lorraine Schol De Jong's Dutch ancestors, dating back to the mid-nineteenth century.

The Bernard and Winifred De Jong series dates from 1935-2009 and is comprised of correspondence, photographs, and family memorabilia for Bernard and Winifred De Jong as well as their children. The series includes records of Bernard De Jong's enlistment in and honorable discharge from the armed forces, as well as letters he received from fellow servicemen during his trip home to visit his brother, Frederick, as the latter suffered from the illness that eventually killed him. Also included are letters home from Bernard and Winifred's son John, who served in the Navy during the Vietnam War. Memorial documents for Bernard, Winifred, and their son John complete the series.

The Eunice Florence De Jong series dates from 1915-2011. Central to this series is collected correspondence between Eunice and her extended family. Especially notable are the faxes exchanged between Eunice and her sister Joanne, as well as Joanne's children, as Joanne struggled with ALS and her family attempted to find appropriate in-home care. The series also includes autograph books from Eunice's youth, collected newspaper articles on topics as varied as health and cats, and materials related to her family's Dutch heritage.

The Correspondence of Katherine, Eunice, and Jeanette De Jong series dates from 1965-1979 and contains letters and cards from Katherine's grandchildren (Eunice and Jeanette's nieces and nephews), primarily John De Jong and Mary De Jong Gantz. The correspondence discusses weather and health, as well as the school and career progress of the grandchildren as they advanced from the University to the workforce.

The Correspondence of Eunice and Jeanette De Jong series dates from 1968-2002 and is comprised of letters and cards from family and friends. Early correspondence in this series is addressed to Katherine as well as Eunice and Jeanette, and correspondence continues beyond Katherine's death, at which point it is addressed to Eunice and Jeanette alone. Much of the correspondence comes from Eunice and Jeanette's nieces and nephews, and, eventually, the children of those nieces and nephews.

The Artifacts series is comprised of the family's personal items and gifts, including Winifred De Jong's wallet, a cap made for Eunice De Jong by her sister Jeanette, John De Jong's baby shoes, and a set of handkerchiefs given as gifts. Also included is a crocheted angel, a maypole, a Christmas ornament, a day book, and a fan used during church services.

The Audiovisual series dates from 1972 to 1984, and includes recordings of music, poems, and church services. The languages used on these recordings include both English and Dutch.