The İslâm Ansiklopedisi (İA) (transl. Encyclopedia of Islam) is a Turkish academic encyclopedia for Islamic studies published by Türkiye Diyanet Foundation [tr].

The decision to begin the encyclopedia project was made at the 1st Turkish Publications Congress in Ankara on 2–5 May 1939. In response to this Congress, the Turkish Minister of National Education Hasan Âli Yücel sent a letter dated 9 May 1939 to the rector of Istanbul University requesting that the Encyclopaedia of Islam be translated into Turkish.^[1]

The project was initially led by Ahmet Hamit Ongunsu [tr], Dean of the Faculty of Letters of Istanbul University, but soon Abdülhak Adnan Adıvar was appointed leader of the project. The first fascicle of the Encyclopedia of Islam was published in December 1940. The project's first headquarters was in the Institute of Turkology's building, later used as the Istanbul University Professors' House. The headquarters was moved to Seyyid Hasan Pasha Madrasa in 1947. The encyclopedia was completed in 1987.^[1][2]

Initially, in 1939,^[1] the İA was proposed to be a translation of the first Encyclopaedia of Islam (EI1, 1913–1938) into the Turkish language because the EI1 had only been introduced in English, French and German.

However, while preparing the İslâm Ansiklopedisi many articles of the EI1 were revised, expanded and corrected, and the work ultimately "had the dual purpose of amending Orientalist scholarship and elaborating on the Turkish contribution to Islamic tradition".^[3]

The result was that the İslâm Ansiklopedisi became a work consisting of 15 volumes instead of the originally proposed five. Some articles of the İA have been in turn included into the second Encyclopaedia of Islam (EI2, 1960–2007), and EI2 articles refer to many articles of the İA.^[4]

From 1966 until 1987, the editor-in-chief of İslâm Ansiklopedisi was the Tahsin Yazıcı, a Turkish scholar of Persian literature, who personally contributed more than 150 articles to the work. The previous editor-in-chief was Ahmed Ateş.^[5]

Türkiye Diyanet Vakfı İslâm Ansiklopedisi (TDV İA or DİA) is sometimes regarded as a successor to İslâm Ansiklopedisi.^{[citation needed]} DİA is a completely original work, which was published in 44 volumes from 1988 to December 2013, with two supplementary volumes published in 2016. It contains 16,855 articles in total.^{[citation needed]}

The academic quality of DİA is recognized by Turkologists and Turkish-speaking scholars of Islamic studies.^[6]

The transliteration system of the İslâm Ansiklopedisi has become a de facto standard in Oriental studies for the transliteration of Ottoman Turkish texts.^[7] For phonetic transcription the dictionaries of New Redhouse, Karl Steuerwald and Ferit Develioğlu have become standard.^[8] Another transliteration system is that of the Deutsche Morgenländische Gesellschaft (DMG), which handles any Turkic language written in the Arabic script.^[9] There are few differences between the İA and the DMG transliteration systems.

• 2014: Presidential Culture and Arts Grand Awards^[11]

• Encyclopaedia of Islam
• Encyclopædia Iranica