Our journals received nearly 20’000 manuscript submissions in 2013, or about 75 submissions per business day. It is a logistical challenge to handle this number of incoming manuscripts, to screen them appropriately, expedite them to external peer-review and to communicate with authors to keep them informed and advise them on revisions. More than 100 in-house editors are employed by MDPI to handle the manuscripts through peer-review, to manage the correspondence with referees and authors, and to guide accepted manuscripts through copy-editing, English editing and production. However, the most valuable part of the work is done by external academic editors and referees that generously donate their time to ensure that our journals publish high quality work.

Peer-review remains the cornerstone of formal academic publishing. It ensures that journals publish scientific and relevant papers, and often helps authors to significantly improve their paper prior to publication. It is of course also a filtering and selection process that tries to identify those papers which are most suitable for publication. For referees, reviewing provides an opportunity to keep up with latest research results in a rapidly advancing, information-based society. The quality and reputation of a journal depends critically on the peer-review of each and every paper, and the scrutiny applied by the referees and academic editors. The selection of referees is therefore critical, which is why we carefully select them after screening literature databases for their previous publications on the topic, and checking their academic background.

Being committed to a thorough peer-review process, we wish to thank all of our reviewers. To this end we recently published Acknowledgements to Reviewers for 85 of our journals, which list the names of the referees that kindly reviewed manuscripts for the journal in 2013 (for smaller journals that published only a handful of articles we did not publish the list, in order not to compromise the anonymity of the referees). The links to the acknowledgments for 2013 are collected here.

Rejection and Acceptance Rates

The overall rejection rate across all our journals in 2013 is 50.3%. This number is based on 18,627 manuscripts on which a decision was made within 2013, of which 9,374 manuscripts (50.3%) were rejected and 9,253 (49.7%) accepted for publication.

For journals covered by Web of Science, the overall 2013 rejection rate is 52.6%, based on 14,321 manuscripts that received a decision of which 7,540 manuscripts were rejected and 6,781 accepted. The table below gives the rejection and acceptance rates for each of our journals covered by Web of Science.

Table 1. Publication overview for MDPI journals indexed by the Web of Science.

Journal	Rejected	Accepted	Total Decisions	Rejection Rate	Acceptance Rate
Atmosphere	18	29	47	38%	62%
Energies	789	334	1123	70%	30%
Entropy	210	285	495	42%	58%
Forests	97	67	164	59%	41%
IJERPH	581	476	1057	55%	45%
IJMS	1583	1344	2927	54%	46%
Marine Drugs	196	320	516	38%	62%
Materials	508	374	882	58%	42%
Micromachines	14	33	47	30%	70%
Molecules	1176	1008	2184	54%	46%
Nutrients	249	313	562	44%	56%
Polymers	64	63	127	50%	50%
Religions	18	43	61	30%	70%
Remote Sensing	391	345	736	53%	47%
Sensors	1154	977	2131	54%	46%
Sustainability	138	300	438	32%	68%
Symmetry	13	12	25	52%	48%
Toxins	54	164	218	25%	75%
Viruses	92	174	266	35%	65%
Water	195	120	315	62%	38%

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