One disk of the double album was recorded at Pentangle's live concert in the Royal Festival Hall, which took place on 29 June 1968; the other was recorded in the studio. The material is the most wide-ranging of Pentangle's albums, including folk songs, jazz classics, blues, early music and Pentangle's own compositions. The album cover was designed by Peter Blake, better-known for his design of The Beatles' Sgt. Pepper's Lonely Hearts Club Band album.
In his retrospective review for Allmusic, Matthew Greenwald called the album, "probably the most representative of their work... In all, Sweet Child is an awesome and delightful collection, and probably their finest hour."
Sweet Child was originally released in the UK, as a double LP, on 1 November 1968 as Transatlantic TRA178. The US release, in the same year, was Reprise 2R56334. A CD version was released in 1992 as Line TACD9005. Some of the stage banter in the live section has been cut from this version. In 2001, a digitally remastered version was released as Castle CMDDD132, including several versions of some of the studio takes and some additional songs from the Festival Hall concert: "Hear my Call", "Let No Man Steal Your Thyme", "Bells", "Travelling Song", "Waltz", "Way Behind The Sun" and "Go and Catch a Falling Star".