The goal of informatization of Croatian libraries is creating a union database of bibliographic and authority records through the process of shared cataloging, which would ultimately result in creating an integrated online catalogue. The main preconditions for achieving this goal are organizing programs for cooperative cataloging, with predefined cataloguing procedures which would save time and ensure high quality of records. The paper presents the results of the cooperative cataloging on the example of the network of libraries that use the library system ZaKi. The table shows the data with the total number of bibliographical records contributed by each library, and the number of records used by other libraries in the period from 2011 to 2013. Special attention is given to the three county libraries: Zagreb City Libraries, the City Library Rijeka, and the City Library Marko Marulic Split.