Until early 2006, the index was available by a CD subscription; now it can be found online on the Vaughan Williams Memorial Library website, maintained by the English Folk Dance and Song Society (EFDSS).
The primary function of the Roud Folk Song Index is as a research aid correlating versions of traditional English-language folk song lyrics independently documented over past centuries by many different collectors across (especially) the UK and North America.
It is possible by searching the database—for example by title, first line(s), or subject matter (or a combination of any of a dozen fields)—to locate many of the variants of a particular song.
The database is recognised as a "significant index" by the EFDSS[4] and was one of the first items to be published on its web site after the launch of the online version of the Vaughan Williams Memorial Library in 2006.
[further explanation needed] The Index cross-references to the Child Ballad number, if one is available for the particular song in question.
The index was compiled and is maintained by Steve Roud, formerly the Local Studies Librarian in the London Borough of Croydon.
[5] In 1993, Roud implemented his record system on a computer database, which he continues to expand and maintain and which is now hosted on the website of the Vaughan Williams Memorial Library.
It is proposed to include Indigenous American songs, as transcribed around the years 1900 to 1920 by Natalie Curtis.