Diamond Open Access (DOA) refers to publishing models where ownership lies with the academiccommunity (scholarly- or library-led). DOA makes articles and books open available immediately and without embargo, does not charge fees to readers and/or authors and keeps copyright in the hands of the author. DOA contributes to a diverse publishing system by making it possible for researchers with small grants to publish Open Access and by publishing on topics and in languages that commercial publishers tend to set aside. Despite these advantages, DOA journals and publishers are struggling. With little to no budget, reliance on volunteering and a culture of evaluation built around impact factors, DOA is pushed into a tight spot. With the program Strengthening Diamond Open Access in the Netherlands , the Dutch consortium of university libraries UKB, aims to strengthen, make more sustainable and encourage DOA journals and publishers. The action plan describes the context, problem definition, stakeholders, timelines and projects of the program.