Collection management has undergone important changes in recent years. New paradigms in the organization of library activities are developing, and cooperation is more and more a key point. Both internal cooperation between collection development, cataloguing and reference departments, and cooperation outside, with other libraries, are necessary today to face the challenges that digital resources bring about and problems still unsolved, like archiving. Cooperation is also fostered by the implementation of software products that support collection development activities. An example is ITSO CUL, a system realized by Cornell University Library.