The relevance and value of books in scholarly communication from both sides, the scholars who chose this format as a communication channel and the instances assessing the scholarly and scientific output is undisputed. Nevertheless, the absence of worldwide comprehensive databases covering the items and information needed for the assessment of this type of publication has urged several European countries to develop custom-built information systems for the registration of books, weighting procedures and funding allocation practices enabling a proper assessment of books and book-type publications. For the first time, these systems make the assessment of books as a research output feasible. This paper resumes the main features of the assessment systems developed in five European countries / regions (Spain, Denmark, Flanders, Finland and Norway), focusing on the processes involved in the collection and processing of data on books, weighting, as well as their application in the context of research funding assessment.