The interoperability of the OAI-PMH protocol provides for indexing self-archived documents worldwide, namely in major web search engines and OAI harvesters (Google, Google Scholar, OAIster, etc.).

Depositing a document in an open archive allows you to target a wider readership (worldwide, including in developing countries and in institutions that haven’t subscribed to the journal that published the article).

It allows you to improve your readership and your visibility in the eyes of your peers and funding sources.

 Steve Lawrence (Nature, Vol 411, no. 6837, p. 521, 2001) has demonstrated in a widely cited study, that "on average there are 336% more citations to online articles compared to offline articles".

Several other publications tend to agree (refer to the Open Citation Project’s bibliography).

Broadening an article’s life cycle beyond its publication in a journal. For example, on ArXiv, preprints receive 20% of all their citations before they are published.

Gaining access to new bibliometric indicators (download rate, etc.).

Facilitating the writing of your progress report: various bibliographic formats are available for data extraction and institutional repositories can be interconnected. For example, HAL is a source of information for the CRAC (Compte-Rendu Annuel du Chercheur - yearly research progress report) and the CNRS (Centre national de la recherche scientifique - French agency for scientific research) LabIntel database.

In France, increasing numbers of institutions are formalising their Open Access policy by setting up institutional archives:

• Some of them have signed the Berlin Declaration on Open Access to Knowledge in the Sciences and Humanities

• Others have implemented institutional mandates for the compulsory depositing of their members’ scientific output.

Public research funding bodies are moving in the same direction:

The ANR (French National Research Agency) is encouraging researchers to self-archive their publications in open archives (French web page)

At the European level, the main goal of the OpenAIRE project (Open Access Infrastructure for Research inEurope) is to implement the European Commission’s decision to make Open Access mandatory for all scientific publications produced with FP7 funding. This ambitions project, named Open Access Pilot, concerns approximately 20% of the FP7 budget (i.e. 10 billion euros) and brings together 38 partners from 27 EU countries and involves researchers working on seven topics (energy, environment, research infrastructure, social sciences, socio-economic sciences, health, and information and communication technology). The project also concerns research publications produced with the funding of the European Research Council (ERC).

Having a direct and quick way of ensuring scientific communication between researchers.

Creating a research network, creating and strengthening collaborations.

Making it easier to find experts and facilitating the creation of partnerships (at the international level).

Developing a bibliographic database ("institutional bibliography") useful for the scientific community.

Granting open access to a large scientific corpus, without technical, financial or legal barriers.

Ensuring the citability of digital documents (permanent URLs).

Ensuring the long-term archiving of documents and the preservation of data.