As infrastructures, policymaking activities, and funding for open access book publishing evolve, the question of how diamond OA might best be implemented for books becomes more pressing. A review of diamond OA criteria for journals is a good place to start.
Diamond open access (OA) is growing in prominence and support, with—to give only a few examples—the UNESCO Global Diamond Open Access Alliance, the Aligning and Mutualizing Nonprofit Open Access Publishing Services Internationally (ALMASI) project across Europe, Africa and Latin America, and the European Diamond Capacity Hub (building on the work of the Developing Institutional Open Access Publishing Models to Advance Scholarly Communication (DIAMAS) and Creating a Robust Accessible Federated Technology for Open Access (CRAFT-OA) projects) all launching in recent months. Broadly, these initiatives seek to coordinate, streamline, and accelerate work that has already been done in many places, as well as to support new presses and publications, in order to establish diamond OA as a viable route for scholarly publications.
But, at least for now, they will focus primarily on journals, a trend that mirrors the overall development of OA to date, in which books have been viewed as more complex and less of a priority and have been slower to transition to OA.
The authors of this piece all work closely with OA books in different capacities, and we are keen to expand discussions around diamond OA to include long-form publications, a desire that we believe is shared by the organizers of the projects we have mentioned and by others working in OA publishing. This piece stems from our work as members of the Open Scholarly Communication in the European Research Area for the Social Sciences and Humanities (OPERAS) OA Books Special Interest Group (SIG).
Books matter enormously to many disciplines, particularly in the arts, humanities and social sciences, where they are often the primary outlet for new work and therefore critical to academic research. A recent article by Grady et al. (2025) summarizes the reasons OA is important for books, including increased dissemination and citation, a declining print model, and a rise in the number of policy mandates for OA books—a trend that the recently concluded Policy Alignment of Open Access Monographs in the European Research Area (PALOMERA) project has aimed to understand and accelerate. It is true, however, that books are different from journals in many ways, including how they are written (often by a single author, unlike a journal issue, which always contains articles by different authors); their role in an author’s career, since they often represent many years of research and writing in a single output; the longer timeline of their production; the increased editorial and production labor they require; the variety of business models that fund their publication; the range of open licenses that may be appropriate for their content (including for books that focus on local and/or Indigenous knowledge); and their established dissemination routes (both open and closed). These considerations should inform our thinking about how diamond OA can best be implemented for books.
In this article, we do not intend to define diamond OA for books, but to build on a conversation about how to develop diamond models within book publishing that has already begun in various places, including the Second Global Summit on Diamond Open Access in Cape Town in December, 2024 and the recent chapter by Gatti et al. (2025), “Beyond ‘No Fee’: Why Diamond Open Access Is Much More Than A Business Model.”
It is important to note that we all work in a European context, so while we are mindful of the different systems that exist, for example, in Latin America, our primary focus in this piece is the landscape in Europe.
Below, we will examine current standard criteria for diamond OA journals, including the Diamond OA Standard (DOAS) and the Operational Diamond Open Access Criteria for Journals from DIAMAS, and consider the ways in which these standards might be relevant to books.
The DOAS standards define quality criteria for journal publishers and journal publishing service providers. Even at the drafting stage, it was clear that some of these criteria could and should be applied to book publishing. However, book publishing also has specific characteristics that make a straightforward transfer of these criteria impractical.
With the introduction of the European Diamond Capacity Hub (ECDH), the Diamond Discovery Hub, and the broader infrastructure and support systems designed for diamond journals in Europe, the establishment of criteria that would allow book publishers to be included as part of this work has become increasingly important.
Based on the key elements of DOAS, the Operational Diamond Open Access Criteria for Journals were developed to enable a binary classification of journals: those that qualify as diamond journals (and can therefore be included in the Diamond Discovery Hub) and those that do not. It is worth considering whether a similar set of criteria could be established for books, and how such a binary classification would work in the book publishing sector. In other words: can we do this for books—and should we?
Both DOAS and the Operational Diamond Open Access Criteria for Journals were refined through consultation with the community of interested publishers and editors as part of the DIAMAS Project. For journals, it was possible to carry out such consultations in many European countries where the early forms of “capacity centers” (national platforms for OA journal publishing or associations of editors and publishers of OA journals) already existed and where in some countries there is even a long-established tradition of publishing diamond OA journals.
By contrast, national or regional communities of book publishers that could be recognized as diamond OA are, with a few exceptions, still emerging. Although promising signs exist, these communities are generally smaller in scale and at earlier stages of development. Nonetheless, it is necessary that any criteria for books are developed through a similar process of dialogue and consultation: as we lay out below, the book landscape is varied, with a wide variety of cultures and practices that must be taken into account.
It is also important to note that, since the diamond journal landscape is more established, it made sense for the criteria to be used to classify journals and to include or exclude them from diamond services. Since the landscape for books is less developed, it may be that the criteria for books should be used in a more descriptive way, at least for now, with the expectation that they will evolve as diamond OA book publishing becomes more established.
With that in mind, we emphasize that our own exploration of the criteria below is not comprehensive. We have shared what seem to us to be the most significant areas of divergence between books and journals, but there are more that could be addressed, and possibly some that we have not considered. As we state above, this piece is intended as a contribution to an ongoing conversation, and not the final word.
One way to tackle these questions is to examine each of the six Operational Diamond Open Access Criteria for Journals and consider the challenges that arise when attempting to apply them to books.
Before evaluating each of these six criteria individually, a fundamental difficulty emerges: what exactly should be considered the unit for determining whether something qualifies as diamond OA? For journals, this is straightforward—the diamond label is assigned to entire journals rather than to their publishers or individual articles within them.
For books, the concept is less clear. Individual book chapters, whether in authored or edited volumes, are certainly not the appropriate unit of classification. The most straightforward approach would be to apply the classification at the level of individual books. But a system requiring decisions for each title separately, along with the maintenance of registries of diamond books, would be complex and resource intensive. A more pragmatic approach would be to classify publishers (or specific imprints), but, in practice, most publishers employ multiple OA models across different publications. Only a very small number operate entirely under a diamond model.
The most logical solution seems to be to assign the diamond OA label to specific book collections or publishing series. For some publishers, this distinction could be easily implemented, but publishing practices across Europe, and globally, are highly diverse, with many publishers not organizing their output into clearly defined collections or series.
Beyond this fundamental issue, there are also a number of specific challenges in applying each of the six operational criteria to books.
Let us now examine the six criteria in turn:
“1. Persistent identification: The journal should have a valid and confirmed ISSN (https://www.issn.org/).”
A fundamental identifier exists for books as well, the ISBN, but the relationship between the identifier, title, individual editions, and publication years is handled differently than for journals. For journals, there is one ISSN for the print and another for the electronic edition, and volume and issue numbers are identical across both formats, making it easy to identify the issues of the diamond journal in question. The situation with books is somewhat more challenging—ISBNs and DOIs (book-level identifiers) have their own complexities, and the way identifiers are assigned to different versions, editions, or formats of books is still not fully adapted to online book publishing, nor fully aligned among book publishers. The system of identifiers therefore does not yet adequately support the option of bringing together all manifestations of the same book under a single identifier (as it does in the case of journals). It is problematic to base the classification criteria for diamond OA on a system that is still in transition—book publishers will need to align on unified practices for the attribution of persistent identifiers for OA books and chapters if a shift to diamond is desired. (See PALOMERA recommendations for publishers: https://doi.org/10.5281/zenodo.14049031, p.47.)
“2. Scholarly journal: The journal should be a scholarly journal that selects papers via an explicitly described evaluation process before and/or after publication, in line with accepted practices in the relevant discipline (See also DOAS https://doi.org/10.58121/Z15S-JY03).”
Although this criterion primarily aims to ensure the implementation of an independent and objective review process, it is not rigidly prescribed even for journals, with disciplinary differences being taken into account. Nevertheless, the practice of peer review in scholarly journals has become far more standardized across disciplines and geographical regions over recent decades than is the case for books. Even within Europe, there are very different traditions of peer review for books (for example, the tradition of non-anonymous reviewing in Central and Eastern Europe and elsewhere), as well as varying practices regarding the extent of editorial intervention depending on the type of book. Furthermore, peer review and editorial assessment for books may occur at different stages of the publishing process, from the evaluation of manuscripts to post-publication reviews, and the peer review practices themselves could be evaluated at the publisher level (as DOAB does), the series level (as OpenEdition does), or the title level (as SCiELO does). (On the diversity of peer review practices for books, see Deville, Findanis & Stern (2024)). Each approach has its own reasoning and cultural context—but once again this returns us to the question: what is the unit being assessed as “diamond”?
Despite these differences in practice, across language areas, across disciplines, etc. (i.e., bibliodiversity), there is still a strong emphasis on securing and upholding high quality standards in book publishing, which must not be lost in considering peer review for diamond OA books. There is a need for a study that maps these different practices into a typology, so we can better understand their variety and where each is used and why.
“3. Open Access with open licences: All outputs of the journal should be Open Access and carry an open licence that is included in the article-level metadata.”
While, in practice, the most open licenses (such as Creative Commons Attribution—CC BY) are still not adopted by all journals, they are nevertheless dominant among OA journals, both from nonprofit and commercial publishers. Many funders and policymakers also mandate or at least strongly recommend the use of such licenses for journal articles. But no similar consensus has yet been reached regarding recommended or “best” licenses for books, and there are various reasons why CC BY may not always be the most appropriate choice. A number of uncertainties persist among both book publishers and authors. (See for example PALOMERA recommendations on licensing policies: https://doi.org/10.5281/zenodo.14049031, pp. 21–22.) In addition, the question is once again relevant: what is the “diamond” unit whose outputs must all be openly licensed (book, series, publisher)?
“4. No fees: Publication in the journal is not contingent on the payment of fees of any kind (e.g. article processing charges or membership dues). The journal should state this as such on its webpage. Voluntary author contributions and donations are allowed, if this is not a condition for publication.”
For journals, the financial arrangements are typically managed by the publisher. (The DIAMAS definition of a publisher is: an entity with ‘legal, ethical, or/and scientific responsibility for academic publishing’. See https://www.fecyt.es/sites/default/files/users/user378/doas_prc_003_0.pdf.) Even if article processing charges (APCs) or voluntary author contributions are involved, the publisher typically handles all administrative aspects of payment and cost recovery. In book publishing, however, authors and editors often take a much more direct role in jointly securing the funding needed to cover production costs, and they may be actively involved in various stages of the publishing process (such as manuscript preparation, editing, translation, proofreading, and design).
Especially among small, nonprofit publishers, it is common for the publication of a book to depend on the author’s ability to secure at least partial funding, whether through project grants, institutional support, donations obtained by the author, or even personal funds. There also exist mixed models in which voluntary contributions from some authors, together with other sources of revenue, will support the publication of a number of OA books with no compulsory fees being charged to anyone.
These arrangements are sometimes informal (with financial conditions for publication not transparently listed on the publisher’s website but rather agreed upon individually).
It should be noted that author participation in securing publication funding is not a new phenomenon arising with OA; it was also common in the era of print-only publishing. The costs involved are often low: in many countries, and among many small academic publishers, it is possible to publish OA books for much less than the book processing charges of large international publishers.
The scope for voluntary contributions and donations is therefore very wide in OA book publishing, and the joint efforts of author(s) and publisher can be effective in securing these. This must be taken into account when developing diamond criteria.
It is also worth noting that OA book publishers often sell certain formats while making others freely available (e.g., charging for paperback and hardback copies while the digital versions are free); the sales revenue can help to fund publication so that authors are not charged fees. There are also models that depend on subscription to closed access books to fund the publication of OA books, or so-called “delayed OA” models whereby a book is made OA once it has attained a certain level of sales. Whether any of these models of revenue raising should disqualify a book/series/publisher from diamond status might also be a matter of debate.
(For more detail on the different models used to fund OA book publishing, see ‘Business models for OA book publishing’, OA Books Toolkit, revised November 2024, and ‘COPIM – Revenue Models for Open Access Monographs 2020’, Penier et al., October 2020.)
“5. Open to all authors: Authorship in the journal should not be limited to any type of affiliation. Any author can submit an article that is in line with the aims and scope of the journal.”
This is another area where practices in journal publishing and book publishing diverge. Even small, nonprofit journal publishers, scientific associations, and research institutions rarely restrict publication only to their own members or staff. Most journals today seek a wide range of contributors, and although many articles may indeed be authored by affiliated researchers, this is almost never a formal requirement in the journal’s submission guidelines. By contrast, small book publishers, particularly those connected to institutions, often lack the financial and human resources to accept manuscripts from unaffiliated authors and state this clearly in their policies.
Although such a restriction formally excludes non-members or non-employees, the existence of these publishers nonetheless increases the chances for many authors to publish OA books without a fee, thereby supporting equity and inclusion, especially for authors outside the Anglophone world. Such a restriction might also be necessary in the early stages of a publisher’s development, before it becomes able to accept authors from elsewhere. More consideration of how to support publishers that would like to expand beyond their own institution’s authors is needed.
This area is therefore an important one to consider when defining diamond for books: should publishers that are only able to support authors from their own institution be excluded from the diamond classification, and if so, what would the consequences be?
“6. Community-owned: The journal title must be owned by public or not-for-profit organisations (or parts thereof) whose mission includes performing or promoting research and scholarship. These include but are not limited to research performing organisations (RPOs), research funding organisations (RFOs), organisations connected to RPOs (university libraries, university presses, faculties, and departments), research institutes, and scholarly societies. The journal should explain its ownership status on its webpage.”
While this final criterion is highly relevant in the journal publishing landscape dominated by large, profit-driven international publishers, it resonates differently in the world of academic book publishing. Small book publishers, often highly specialized by discipline, region, or language, are frequently organized as small private companies. But this does not mean they are profit oriented; many survive only with public funding support and cannot rely on market-driven success. Their continued existence is crucial for maintaining cultural, linguistic, and epistemic diversity (bibliodiversity). Thus, it is important to carefully design support systems for diamond OA book publishing to avoid inadvertently excluding them. One solution might be to consider instead whether a publisher is “mission driven” (which should be carefully defined and evidenced) rather than whether it is publicly owned or not-for-profit. This is an area that requires careful consideration.
Naturally, this exercise in applying operational criteria for diamond journals to books should not be understood as a criticism of these criteria. On the contrary, they provide an excellent starting point for promoting a transparent and careful discussion about OA in scholarly book publishing that recognizes the richness and diversity of publishing models and the variety of contexts in which publishers operate.
But the challenges in applying these operational criteria to books, and the questions that this exercise has raised, suggest that the concept of diamond OA for books should not yet be used to impose strict classification criteria, but rather as encompassing those forms of mission-driven OA book publishing where the primary goal is ensuring that sound and quality-controlled scholarship can be published openly with a commitment to inclusivity and fairness.
This article has identified a number of areas where further mapping, study, discussion and debate are required to fully understand the current landscape, the prospects for its development in the coming years, and the variables that must be taken into account when considering Diamond OA for books. We are keen to continue the conversation.
10.1146/katina-070925-1
