In light of recent discussions in the scholarly community regarding Special Issues, we would like to clarify MDPI’s editorial approach, safeguards, and oversight mechanisms.
We recognize that endogeny is an issue affecting the scholarly publishing industry and we take concerns around editorial independence seriously. MDPI has clear safeguards in place to manage potential conflicts of interest, and we continue to strengthen oversight of Special Issues as part of our ongoing quality assurance processes.
In line with MDPI’s Special Issues guidelines, Guest Editors are permitted to publish articles in the Special Issues they oversee. To safeguard diversity and inclusiveness within the research area, such contributions must be limited. MDPI’s approach aligns with recognized ethical publishing standards, including those set by COPE and DOAJ. In particular, DOAJ recommends that articles authored by Guest Editors in their own Special Issue should not exceed 25% of the total peer-reviewed content. MDPI journals actively monitor this threshold and clearly communicate the policy to Guest Editors before a Special Issue is launched to ensure transparency and compliance.
It should be noted Special Issues with a very small final number of articles (for example, three) may statistically exceed standard endogeny thresholds if a Guest Editor authors a paper. This can occur despite all submissions being subject to the same independent peer-review and editorial oversight as regular journal articles.
MDPI maintains quality within Special Issues through the same rigorous editorial processes and standard applied to regular submissions to our journals. Before launching a Special Issue, the Editors-in-Chief, Section Editors-in-Chief, or an Editorial Board Member approves both the proposed topic and appointment of the Guest Editor. This ensures that only qualified individuals are authorized to make editorial decisions for Special Issues. Once approved, they continue to supervise the editorial process, monitor all submissions within the Special Issue, provide feedback, and uphold ethical and academic standards.
Our guidelines on Special Issues state that, importantly, articles submitted by a Guest Editor are handled by an independent member of the Editorial Board. These submissions are subject to the same external peer-review and editorial decision-making processes as all other submissions. Guest Editors are not in any way involved in the editorial process, including elements such as peer review selection and publication decisions. Equally, they are excluded from handling papers from collaborators.
We do not believe scale alone determines quality but rather that appropriate editorial safeguards are applied — and these are firmly in place at MDPI throughout the publication process. MDPI’s strong editorial framework has supported the quality and prominence of our Special Issues, which accounted for 62% of MDPI’s published content in 2024 and around 55% in 2025.
