How Green Was My Valley is a 1939 novel by Richard Llewellyn, telling the story through narration of the main character, of his Welsh family and the mining community in which they live. The author had claimed to have based the book on his own knowledge but this was proven untrue after his death; Llewellyn was English-born and spent little time in Wales though he was of Welsh decent.[1] Llewelyn gathered his facts for the novel from conversations with local mining families in Gilfach Goch.

The first edition was published in 1939, set and printed in Great Britain by William Brendon & Son, Ltd., at the Mayflower Press, Plymouth, in Walbaum type, twelve point, leaded, on a toned opaque-wove paper made by John Dickinson, and bound by James Burn.[2] It was published in 8vo size. The first printing included a limited edition run of 200, numbered and signed by Richard Llewellyn. The original print run also included a glossary covering Welsh words and terms at the end of the book.

The successful 1941 film of the book had a cast including Walter Pidgeon, Maureen O'Hara, Anna Lee, Roddy McDowall (as Huw), Donald Crisp, and Barry Fitzgerald. None of the leading players were Welsh. Directed by John Ford, How Green Was My Valley is one of the films selected for preservation in the United States National Film Registry. How Green Was My Valley is available on DVD from 20th Century Fox as part of their 20th Century Fox Studio Classics collection.

The book has twice been adapted by the BBC as a serial for television, in 1960 and 1975. The 1975 production? scripted by Elaine Morgan ? starred Stanley Baker, Si?n Phillips, and Nerys Hughes.

The novel was also adapted as a Broadway musical, called A Time for Singing, which opened at the Broadway Theatre, New York, on 21 May 1966. The music was by John Morris; book and lyrics were by Gerald Freedman and John Morris. The production was directed by Mr. Freedman, and it starred Ivor Emmanuel, Tessie O'Shea, Shani Wallis, and Laurence Naismith.