Intended for Pennsylvania librarians, those who use libraries, and those responsible for libraries, this directory of cooperative library organizations in the state provides information on current operating programs and describes those which may be appropriate for libraries not now participating in them. With few exceptions, the members of the organizations listed are institutions rather than individuals; organizations whose members are personal rather than institutional are listed only if their reported activity indicates institutional commitment to cooperation, and public library systems are not included. The format for each listing includes mailing address, telephone number, name of chief executive officer, expiration date of his term, name of chief administrative officer, purpose statement, basis of organization, description and number of membership, funding sources, publications, and services to nonmember libraries. Tables present services provided through membership, communication links between members, and delivery services available through membership. Also included are lists of the members of cooperative library organizations by name of library and by name of organization. (Author/JD)