In the introduction, we will present the purpose and objectives of this prospective DARIAH Library working group, its relationship to other related DARIAH working groups and the status of its accreditation. In the next part, we will mainly focus on the topic of library collections as data. Current use cases and projects focusing on different (even dynamic) possibilities of providing datasets for researchers will be presented. Relevant activities linked to the European infrastructures EOSC and Europeana will be mentioned. The workshop will include a discussion among participants on topics related to the group's focus and perhaps we will also identify what would be most interesting topics for DARIAH Library WG orientation. We look forward to your participation and active involvement.