The Avestan Digital Archive (ADA) seeks to be a digital archive containing all Avestan manuscripts spread all over the world. The Avesta, the holy book of the Zoroastrian religion, was last edited at the end of the 90s of the 19th century by the German scholar K. F. Geldner. We claim that presently a new edition is needed. The main reasons are:

• In the last decades some manuscripts Geldner did not have access to have become available.
• Geldner did not check by himself all the manuscripts used for his edition. For some of them he had access only to copies or collations by other colleagues. This was the source of several mistakes in his edition.
• The methods of textual criticism have strongly changed since Geldner and many methodological decisions of Geldner seem today unacceptable. The most important one is undoubtedly that he does not record systematically all the variae lectiones (or a selection according to well established criteria), but only the variants he considered important for the establishment of a sure text.
• Even when he checked the manuscript by himself and recorded the variae lectiones, he made mistakes more often than expected.

For all these reasons it has become a true need to provide the scholars with reasonably sure readings of the extant Avestan texts. But a new edition of the Avesta is a huge task: probably more than two hundred manuscripts scattered all over the world have to be checked. Many of them are not available even as microfilms and are only accessible through long stays in Indian libraries. Also the purchase of microfilms from European libraries is not the best way for single researchers to get access to the manuscripts: a lot of them are needed, so that the undertaking quickly gets too expensive and the result is a not easily manageable amount of microfi lms. A printed publication of such an amount of manuscripts is no more feasible, above all because of financial reasons. So it is easy to understand that yet nobody has seriously tried to undertake a new edition of the Avesta, or al least a serious review of Geldner's edition.

In order to solve this problem we have conceived the ADA project. This project seeks, on the one side, to find, to collect and to digitalize all the extant Avestan manuscripts. On the other hand, the ADA Project is developing a tool to provide all these manuscripts with indexes of the passages and to make them thus available on the web for researchers and for the general public. The electronic tool will allow an easy checking of all the manuscripts containing a concrete passage. This research tool can be useful not only for the Old Iranian studies, but also for the textual criticism based on manuscripts in other languages and fields of research. Furthermore, the ADA project seeks to review the manuscript transmission of the Avestan texts in all its aspects, a task which presupposes the complete ga thering and availability of the manuscripts.