Book excerpt: This index is intended as a summary subject-guide to the Arabic manuscripts in the British Library, one of the most importance storehouses of Arab and Islamic documentary heritage in the world. The manuscripts have been arranged into subject categories, and the more important bilingual texts have been included as well as manuscripts in the Arabic language but copied in other scripts. To date only some of the collection has been catalogued, other parts have remained undocumented. With this subject-guide researchers can exploit the full range of this resource.