Purpose: This paper is a critical discussion of the Leiden Manifesto for libraries already engaged in bibliometric practices. It offers practical recommendations based on the work of the European Association for Research Libraries (LIBER) Working Group on Metrics. This work is in the beginning phase and summarizes literature on the topic as well as the experiences of the members of the Working Group. The discussion reflects today’s growing popularity of (quantitative) research assessment which is seen in enthusiasts introducing new metrics (i.e. altmetrics) and by critics demanding responsible metrics that increase objectivity and equity in evaluations.Design/methodology/approach: This paper is the result of the Working Group on Metrics of the European Association for Research Libraries (LIBER) that critically discussed the practicality of the Leiden Manifesto for libraries.Findings: Full compliance with the Manifesto is time-consuming, expensive and requires a significant increase in bibliometric expertise with respect to both staffing and skill level. Despite these apparent disadvantages, it is recommended that all libraries embrace the Manifesto’s principles. To increase practicality it is advised that libraries collaborate with researchers, management and other libraries at home and around the world to jointly design and provide services that can be reused within the library community.Originality/value: Libraries have increasingly been confronted with questions about research assessment, responsible metrics, and the role of digital products in evaluations and funding decisions. Although a wide range of recommendations and initiatives are available (e.g., DORA San Francisco Declaration on Research Assessment) many recommendations are not straightforward enough to be implemented from a library perspective. This paper provides assistance for libraries to implement these principles by acknowledging the heterogeneous backgrounds the libraries may stem from.https://doi.org/10.1108/DLP-01-2017-0004