Ink jet printability is rapidly becoming a requirement for all multipurpose office papers. These papers must have an optimized balance of properties so they can perform equally well under various printing methods such as xerography, ink jet, and thermal imaging. The office paper of today truly must be a multipurpose copy paper capable of providing good toner adhesion as well as controlled absorption of aqueous ink jet solutions. The demand for ink jet paper is increasing rapidly. The global market for cut-size ink jet papers will expand to nearly 1.4 million tons by the year 2000. By that time the global market for all cut-size multipurpose plain printing papers will grow to nearly twenty million tons. The ink jet printing process places a large volume of aqueous ink on the surface of a substrate. The manner in which the substrate handles that volume of ink determines in large part the quality of the print. Multipurpose office papers are composed chiefly of cellulose fibers, inorganic fillers, and chemical additives. All of these components affect the quality of the sheet as an ink jet substrate. The particle morphology, surface area, and surface treatment of PCC fillers affect the ink jet printability of multipurpose office papers. This paper focuses on results from pilot paper machine and commercial trials performed in an effort to turn 'plain' office papers into high quality multipurpose papers capable of meeting or exceeding ink jet print quality specifications.