Abstract: Papers of Sidney D. Wells, a chemical engineer and inventor involved primarily in pulp and paper making processes. Though he did frequent consultant work, most of his professional career was spent working for the U.S. Department of Agriculture's Forest Products Laboratory, Madison, Wis.; Paper Mill Laboratories, Quincy, Ill.; Nekoosa-Edwards Paper Company, Port Edwards, Wis.; Central Fibre Products Company; Combined Locks Paper Company, Appleton, Wis.; and the Institute of Paper Chemistry, Appleton, Wis. The papers concern Wells' professional activities and are often very technical in nature. They include correspondence, reports, reprints of his writings, patents and accounts of the operations they cover, and paper samples. Correspondents include William Leonard Symons and John D. Rue.