The size of digital libraries is increasing, making navigation and access to information more challenging. Improving the system by observing the users’ activities can help at providing better services to users of very large digital libraries. In this paper we explain how the Invenio open-source software, used by the CERN Document Server (CDS) allows fine grained logging of user behavior. In the first phase, the sequence of actions performed by users of CDS is captured, while in the second phase statistical data is calculated offline. This paper explains these two steps and the results. Although the analyzed system focuses on the high energy physics literature, the process could be applicable to other scientific communities, with and international, large user base.