The album begins with a poem accompanied by electronic sounds, and these sounds also appear at the close of the album – vinyl pressings of the album continue the sounds into the album's run-out groove, causing them to play continuously until the record player's tonearm is lifted. Tape and CD album versions employ a slow fade.
The album was mixed and released in both stereo and quadraphonic. (The quadraphonic mix includes some variations from the stereo version, including an extended ending of "To Share Our Love" and a reprise of the electronic sounds from the beginning of the album after "So Deep Within You.")
On the Threshold of a Dream was released on 25 April 1969 in the UK and 30 May 1969 in the US.On the Threshold of a Dream provided The Moody Blues with their first British number 1 album, and also boosted their American fortunes by becoming their first Top 20 album there. The album also enjoyed lengthy stays in both album charts. By contrast, its one and only single, "Never Comes the Day", was a commercial flop.
In March 2006 the album was completely remastered into SACD format and repackaged with nine extra tracks. In 2008 a remaster for standard audio CD was issued with the same bonus tracks.