The records are primarily Bader's business papers. They include some calculations and estimates by others, but also John A. Bader II's engineer's field book, diaries of trips (1917-1918), and job notes. Ten pocket notebooks are from the period of his father's business (1904-1922).

Records of John A. Bader II's business include eight volumes (1933-1958), containing profit and loss statements, cost accounting for jobs, and records of checks paid. There are also loose accounts, auditor's reports, licenses, and tax returns. Files on individual construction jobs include daily reports on time and materials, correspondence with subcontractors and others, blueprints, invoices, statements and payrolls, purchase orders, building permits, employee accident reports, price estimates, specifications, insurance binders, and newsclippings. The largest number of jobs are for William du Pont Jr. and his sister, Marion du Pont Scott. Others include Delaware Park, the Goldey Beacom School of Business, alterations to the Delaware Trust Building, Amalgamated Leather Companies, Inc., the Atlas Powder Company, and Safeway Stores, Inc.

Also included are an account book of household and business expenses (1957-1963), weekly payroll sheets (1954-1961), and records of employee tax and social security deductions (1948-1961).