The Subseries A contains bills paid by William du Pont, Jr. from the year 1919 when he and his first wife Jean L. Austin started their household in Rosemont, near Newtown Square, Pennsylvania, up to 1964 when he divorced his second wife Margaret Osborne. Bills for the last year of his life (William du Pont, Jr. died December 31, 1965) are not in the subseries.

Material collected in Subseries A primarily covers expenses for the family household in Rosemont, Pennsylvania from 1919 to 1941 (when William du Pont, Jr. and Jean L. Austin divorced and William moved to his estate Bellevue, north of Wilmington, Delaware). Bellevue expenses commence in 1925, when William du Pont, Jr. established horse stables and a dairy farm, and constitute the bulk of the records, 1941-1964. Additionally, the subseries documents expenses for other family estates: Walnut Hall Farm at Boyce, Virginia (from 1927); Fair Hill, Maryland (from 1928); Saratoga Springs, New York (from 1928); Altama, Georgia (1928-1932); summer house at Fishers Island, New York (1930s-1950s); and Easton, Maryland (bought in October 1953).

Invoices and receipts document all of the important construction and alteration projects undertaken on the estates and farms, especially at Bellevue Hall. Work was done on the main house, farm houses, barns, kennels, stables, horse race tracks, indoor and outdoor tennis courts, swimming pools and auxiliary buildings, and landscaping and gardening. Household expenses include repairs, furnishings, appliances and decoration, utilities, telephone and telegraph services, coal and ice, family trips, children's school tuition, food and groceries for family, farm workers, and caretakers of horses and dogs, blacksmith and veterinarian services, personal clothes, subscriptions, membership dues, farm machinery and personal cars, animal feed, seeds, horse racing and training equipment, tennis equipment, and court and track maintenance. Contractors and suppliers were usually local. Many of them worked for William du Pont, Jr. for a long time such as William H. Doyle, Inc. / Doyle and McDonnell, Inc. (nursery and general contracting of Berwyn, Pennsylvania), John A. Bader II and J. Warren Barkley (Wilmington, Delaware) whose bills contain descriptions of the jobs performed.

Files also contain:.

Fee receipts for horse registration at the Jockey Club (New York, New York), horse show and race entries, stable and seats rentals at various events (see the list in Series I. Correspondence).

Membership fee receipts for national organizations-Association of American Horse Shows / American Horse Show Association, Masters of Foxhounds Association of America, National Steeplechase and Hunt Association, National Horse Show Association, United Hunts Racing Association, Thoroughbred Horse Association, Army Ordnance Association, Horse and Mule Association of America, Percheron Horse Association of America, United States Pony Club, United States Court Tennis Association, American Game Association; California organizations-Los Angeles Tennis Club, California Tennis Club (San Francisco); Delaware organizations-Vicmead Hunt Club, the Wilmington Society of the Fine Arts, Delaware Safety Council, Wilmington Trapshooting Association, Delaware Motor Club (A.A.A.), Brandywine Valley Association, The Wilmington Club, Wilmington Country Club; Maryland organizations-Foxcatcher Hounds Hunt Club, Eastern National Livestock Show; New York organizations-Meadow Brook Steeplechase Association, Saratoga Reading Rooms, The Saratoga Association, Rockaway Steeplechase Association, Keystone Automobile Club, New York, The Jockey Club (New York, New York), Saratoga Golf Club, The River Club of New York, Turf and Field Club (New York, New York); Pennsylvania organizations-Radnor Hunt, Rose Tree Fox Hunting Club, the Corinthian Yacht Club of Philadelphia; Virginia organizations-Drum Point Gunning Club, Blue Ridge Hunt Club, Virginia Gold Cup Association, Virginia Horse Breeders' Association, The Virginia Horsemen's Association, Virginia Fox Hunters Association; and the Eastern Horse Club (Boston, Massachusetts); Grayson Foundation (Kentucky).

Receipts of Thoroughbred horse auction agent Fasig-Tipton Company (from 1925) for horses purchased by William du Pont, Jr.

Receipts for state and local taxes: Delaware (1919-1952, 1954, 1960-1964), Georgia (1930-1932), Maryland (1928-1932, 1957, 1959, 1962-1964), New York (1930-1964), Pennsylvania (1919-1935, 1937, 1947-1948), and Virginia (1927-1958, 1961-1964).

Insurance premiums, investment statements, notary and legal services in connection with registration of companies, deeds, tax return preparation, vehicle titles, representation in court.

Subscription fees for professional publications: Official Horse Show Blue Book, The Spur, Racing Calendar, The Rider and Driver, The Blood-Horse, The Thoroughbred Record (Kentucky), American Lawn Tennis, The Field, publications of The American Foxhound Club.

Accounts with companies whose workforce was used by William du Pont, Jr. for personal purposes-Stockford Farms, Inc., and its subsidiaries, Foxcatcher Livestock Co., rental accounts with Bellevue Hall, Inc., Walnut Hall, Inc., office rental from Delaware Trust Building Corporation / Shapdale, Inc., retail company Montpelier Supply Company.

Accounts with employees for their expenses on trips, with clients for boarding horses at William du Pont, Jr. farms; hospital bills for employees, account statements of farm and stable managers, accounts with temporary workers.

Freight bills, arrival notices from railroads which transported horses, cattle, hay, and oats, construction material: Pennsylvania Railroad / Pennsylvania System, Southern Railway Company, the Baltimore and Ohio Railroad Company, Norfolk and Western Railway Company, the Chesapeake and Ohio Railway Company, the New York Central Railroad Company, American Railway Express Company.

Files contain some related correspondence.