Article describing work to extend the coverage of the Flare Index to Treaties at the Institute of Advanced Legal Studies to include key multilateral treaties from 1353 onwards and, in addition, key bilateral treaties from 1353 to 1815. The Flare Index to Treaties is a freely available, searchable database of basic information on over 2,000 of the most significant multilateral treaties and some bilateral treaties concluded between 1353 and the present, with details of where the full text of each treaty may be obtained in paper and, if available, electronic form on the Internet.