Prior to the album's recording in 1986, Testament was known as Legacy. Their lineup consisted of singer Steve "Zetro" Souza, guitarists Alex Skolnick and Eric Peterson, bassist Greg Christian and drummer Louie Clemente. Singer Chuck Billy was a member of another local band named Guilt. He had performed with Legacy on a few occasions and was asked to become the new singer after Souza left to join Exodus. In 1986, the band changed their name to Testament after finding out that there was a jazz band named Legacy. The Testament name was suggested by Billy Milano (from S.O.D. and M.O.D.), who was a friend of the band in the early days.
This was the only Testament album to feature songwriting contributions from Souza, who was credited as the co-writer of all the songs, except for "C.O.T.L.O.D." and "Do or Die", which were co-written by original Legacy singer Derrick Ramirez and Billy respectively. The closing track, "Apocalyptic City", was written by Skolnick and Peterson.
The album's first song "Over the Wall" is Testament's most played song of all time, first played on April 18, 1986 at Ruthie's Inn in Berkeley, California, when Testament was still known as Legacy.