In 1979 the State Library of Pennsylvania awarded a contract of $99,304 to the Pittsburgh Regional Library Center to begin development of an on-line union list of serials for Pennsylvania. This article describes accomplishments of the first contract year, October 1, 1979-September 30, 1980; the second year proposal for which a contract was awarded for $99,848; and accomplishments to date in the second year of the Pennsylvania Union List of Serials (PaULS). Plans for production of the initial core list of 2,580 titles in COM by June 30, 1981 are described. OCLC developments including the introduction of its union listing capability are discussed and implications of these for the long-range future of PaULS are considered. Planning for the third year and beyond is reviewed and possible applications against the file and its usefulness as a tool for regional collection development are presented.