The William Pynchon papers document his career as a prominent counselor and businessman. They do not shed light on his loyalist views. The collection is arranged into two series.

Series I. Legal Records consists of fee and receipt books. Arranged alphabetically by client and then by court session, the court fee books recount the type of services rendered and the fee charged. Case settlement fees, with Pynchon acting as intermediary, are recorded in the receipt books. Legal activities not resulting in a lawsuit are recorded in the legal bee book (B1 F2) and payment receipt book (B3 F1) Additional legal charges may be gleaned from the account books.

Series II. Account Books consists of a ledger, journal, and two daybooks. Entries include household and personal expenses, son's college bills, legal fees, dry goods ship sales, shipping ventures, and miscellaneous business investments. Within each year, Pynchon groups some of his accounts into subject categories: building, "movables," fees, expenses, shop goods, etc.