Table of Contents
- Introduction
- The Origins and Principles of Plan S
- Adoption and Implementation Across Europe
- Impact on Researchers and Research Practices
- Publisher Responses and Market Realignment
- Equity and the APC Conundrum
- Plan S and the Global Scholarly Communication Landscape
- Technological Infrastructure and Policy Synergies
- Looking Ahead: The Future of Plan S and OA in Europe
- Conclusion
Introduction
The European academic publishing landscape has undergone seismic shifts in recent years, with open access (OA) reform taking center stage. Plan S is at the forefront of this transformation, a bold initiative launched in 2018 by cOAlition S—an international consortium of national research funders and charitable foundations. Its mission? To make all publicly funded research publications openly accessible without embargoes and paywalls. The policy officially came into effect in 2021, and as we reach the midpoint of the decade, the time is ripe for a comprehensive evaluation of its impact and the road ahead.
In 2025, Plan S is no longer a theoretical framework or an aspirational policy—it’s a lived reality for researchers, institutions, publishers, and funders across Europe. The academic publishing ecosystem has responded with varying enthusiasm, resistance, innovation, and recalibration. Open access has become more mainstream, but challenges related to equity, business sustainability, and disciplinary diversity remain pronounced. This article delves into how Plan S and academic publishing in Europe have evolved over the past four years, examines its effects on stakeholders, and projects the possible trajectories of academic publishing in Europe for the remainder of the decade.
The Origins and Principles of Plan S
To fully grasp the current state of Plan S, it’s essential to revisit its origins and underlying motivations. Launched in 2018 by cOAlition S, a consortium of research funders, Plan S was designed as a radical intervention to accelerate the transition to open access. Its central mandate was unambiguous: by 2021, all scholarly publications from publicly funded research must appear in compliant OA venues, eliminating embargoes and paywalls. The “S” signifies “shock,” reflecting the initiative’s intent to disrupt the entrenched subscription-based ecosystem and realign scholarly publishing with the principle that publicly funded research should be a public good.
At its foundation, Plan S is built upon ten key principles that aim to reshape academic publishing norms. Among these are the insistence on full and immediate OA, the retention of copyright by authors without restrictive licensing, and a firm stance against hybrid journals—unless they operate under transformative agreements committed to a full OA transition. These principles were not arbitrary but emerged from growing frustration with the slow progress of voluntary OA adoption and the dual-payment burden of hybrid publishing, where institutions often paid both subscriptions and article processing charges (APCs).
To accommodate diverse publishing practices, Plan S outlined multiple compliance pathways:
- Publication in fully OA journals
- Deposit in OA repositories with zero embargo (Green OA)
- Submission to hybrid journals only if covered by transformative agreements with a clear OA transition timeline.
While this flexibility was intended to ease adoption, it initially generated confusion among researchers, institutions, and even publishers. The nuances of transformative agreements require time to be widely understood and implemented effectively. Over the years, stakeholder education and iterative policy refinements have improved clarity, though challenges persist in harmonizing global adoption due to disparities in funding structures and disciplinary publishing traditions.
Critically, Plan S has also spurred broader conversations about equity in OA publishing, particularly regarding APC models that may disadvantage researchers from underfunded institutions. By mandating pathways like Green OA and pushing for cost transparency, the initiative has indirectly pressured the industry to explore more inclusive models, such as diamond/platinum OA, where neither readers nor authors bear direct costs.
Adoption and Implementation Across Europe
One of Plan S’s most significant impacts has been its broad institutional uptake, particularly across European research funders and councils. Early adopters included major national agencies such as the Netherlands Organisation for Scientific Research (NWO), the French National Research Agency (ANR), the Research Council of Norway, and UK Research and Innovation (UKRI), which integrated Plan S mandates into their funding conditions.
As of 2025, the initiative has expanded its reach, with more than 30 national and international funders formally endorsing its principles—a figure underscores its growing influence beyond Europe, including selective adoption in Africa and Asia through partnerships with organizations like the African Academy of Sciences.
This widespread alignment has effectively made Plan S compliance a de facto requirement for researchers reliant on public funding in participating countries. Notably, the European Commission’s Horizon Europe program has reinforced this trend by mandating immediate OA for all funded research, further solidifying Plan S as a benchmark for policy design. However, disparities remain in implementation, particularly in disciplines with entrenched subscription dependencies (e.g., STEM fields dominated by high-impact paywalled journals) and institutions lacking the infrastructure to support full OA transitions.
The initiative’s success has also exposed systemic challenges, such as uneven researcher awareness and persistent inequities in APC-based models, disproportionately affecting early-career and Global South scholars. In response, cOAlition S has recently introduced more nuanced guidance, including expanded support for diamond OA and stricter criteria for transformative agreements to prevent predatory publishing practices. These adjustments reflect a maturing policy framework that retains its original ambition while adapting to the complexities of a global scholarly ecosystem.
However, implementation has been uneven. Western European countries with robust OA infrastructure and funding mechanisms adapted more quickly. Their national repositories, well-funded research libraries, and established OA journals facilitated smoother transitions. In contrast, Central and Eastern European countries faced steeper challenges, often due to limited digital infrastructure, language barriers, and less engagement with international OA dialogues.
Despite these disparities, Plan S has undeniably accelerated OA uptake across the continent. Institutional repositories have expanded, publishers have launched or acquired OA journals, and researchers have become more familiar with rights retention strategies. Even so, questions remain around harmonization, particularly in cross-border collaborations involving funders outside cOAlition S.
Impact on Researchers and Research Practices
For researchers, Plan S has been both liberating and constraining. On the one hand, it has increased the visibility and reach of European scholarship. Articles published under OA licenses are more widely read, cited, and reused, contributing to greater societal impact. For early-career researchers and scholars in less affluent institutions, OA levels the playing field in terms of access.
On the other hand, many researchers have voiced frustration over limited journal choices, especially in specialized disciplines where compliant OA options are scarce. Humanities and social sciences, in particular, have struggled with Plan S compliance due to the dominance of subscription-based journals and the slower pace of OA development in these fields.
The Rights Retention Strategy (RRS), introduced by cOAlition S as a workaround, has empowered researchers to retain rights and deposit Author Accepted Manuscripts (AAMs) in repositories. However, the RRS has met resistance from publishers and remains a point of contention. Researchers also report confusion about journal compliance status, repository requirements, and funding for APCs, all pointing to a need for more coordinated outreach and education.
Publisher Responses and Market Realignment
The traditional publishing industry has had to make significant strategic pivots in response to Plan S. Legacy publishers have pursued various routes to remain viable under the new regime. Many have ramped up OA offerings, launched new OA journals, or converted existing titles into fully OA formats. Transformative agreements—contracts that shift subscription expenditures towards OA publishing—have become a key mechanism in bridging the transition.
However, these agreements have not been without criticism. Some argue that transformative deals reinforce the dominance of large commercial publishers, potentially crowding out smaller publishers and university presses. Furthermore, the high APCs charged by some journals have raised concerns about affordability and equity, particularly for researchers in low-income institutions or regions.
Smaller, independent, and non-profit publishers have had a more complicated journey. Some have thrived by aligning closely with Plan S principles, offering diamond OA models that do not charge authors. Others have struggled with the financial strain of transitioning to OA without sufficient institutional support. The market is gradually bifurcating into publishers that can adapt and scale OA infrastructure and those at risk of marginalization or obsolescence.
Equity and the APC Conundrum
Perhaps one of the most debated consequences of Plan S is its impact on equity, particularly in relation to APCs. While OA has removed paywalls for readers, the cost burden has shifted to authors—or more precisely, their funders and institutions. This “author-pays” model can perpetuate existing inequalities unless carefully managed.
In response, cOAlition S has encouraged funders to support APCs and has promoted transparency through initiatives like the Open Access Price Transparency framework. Nonetheless, there is growing concern that APCs are creating a two-tier publishing system, where only those with financial backing can publish in high-profile OA venues.
The rise of diamond OA, where neither readers nor authors pay, is one of the more promising countermeasures. European institutions and funders are beginning to invest more seriously in diamond OA infrastructure, with initiatives such as DIAMAS and the OA Diamond Journals Study pointing to scalable alternatives. Still, the long-term sustainability of these models remains an open question.
Plan S and the Global Scholarly Communication Landscape
While Plan S is a European initiative, its ripple effects are global. Many international publishers and platforms have had to adjust their workflows, licensing terms, and business models to accommodate Plan S requirements. The policy has added complexity for researchers involved in global collaborations, particularly when co-authors are funded by agencies not aligned with cOAlition S.
In the Global South, there is admiration for Plan S’s ideals but also skepticism about its applicability. The emphasis on APC-based OA is seen as exclusionary, and the lack of alignment with major regional funders complicates compliance. However, Plan S has stimulated broader conversations about inclusive OA and encouraged regional approaches emphasizing multilingualism, local publishing ecosystems, and equitable funding mechanisms.
The UNESCO Recommendation on Open Science, adopted in 2021, echoes many of Plan S’s values but advocates a more flexible, context-sensitive approach. This suggests that while Europe may lead the OA charge through Plan S, future progress will depend on mutual alignment with other global efforts prioritizing inclusivity and diversity.
Technological Infrastructure and Policy Synergies
Infrastructure development is one of the less glamorous but most crucial aspects of Plan S implementation. Repositories, OA platforms, and metadata systems have had to evolve rapidly to support compliance and discovery. Tools like the Journal Checker Tool (JCT) and Sherpa Romeo have become essential resources for researchers navigating the OA terrain.
Policy synergies are also beginning to emerge. Horizon Europe, the EU’s flagship research program, aligns closely with Plan S requirements. National science policies in several European countries are being revised to incorporate OA mandates that reflect or reinforce Plan S principles. The alignment of data policies, research assessment frameworks, and tenure criteria with open science values is gaining momentum, though not uniformly.
At the same time, critics caution against overreliance on bureaucratic tools and rigid frameworks. Continued innovation, user-centered design, and community-driven governance are needed to ensure that OA infrastructure remains adaptable, responsive, and inclusive.
Looking Ahead: The Future of Plan S and OA in Europe
Thus far, Plan S has firmly established OA as the norm rather than the exception for publicly funded research in Europe. But its journey is far from over. Several future-facing questions now demand attention: How can OA models be financially sustainable for all stakeholders? What does a post-transformative agreement publishing landscape look like? Can equity be preserved as OA becomes more entrenched?
A few trends likely shape the next phase. First, the shift from APCs to collective funding and library-led publishing models may gain momentum, especially as resistance to high publishing costs intensifies. Second, disciplinary diversity in OA publishing will likely grow, with new models tailored to the humanities and social sciences. Third, open peer review, interoperable repositories, and alternative metrics will continue challenging conventional notions of academic prestige and impact.
Plan S has catalyzed an irreversible transformation. It has redefined expectations, disrupted long-standing norms, and forced stakeholders to reimagine the economics and ethics of publishing. Its full impact will only be measurable in the long arc of scholarly communication history, but its legacy is already secure as a turning point in Europe’s academic publishing narrative.
Conclusion
Plan S has brought both clarity and complexity to the European academic publishing ecosystem. By forcing the issue of open access into the spotlight, it has empowered researchers, pressured publishers, and reshaped policy landscapes across the continent. While not without its flaws and unintended consequences, the initiative has delivered on its core promise: to make research more accessible, reusable, and impactful.
The years ahead will require a balance of ambition and pragmatism. Stakeholders must continue to collaborate across institutional, disciplinary, and national boundaries. Infrastructure must evolve to support new models of knowledge sharing. And above all, the spirit of openness must be preserved—not just in access, but in governance, innovation, and intent. The future of academic publishing in Europe is open, in every sense of the word.