After winning a legal battle with Epic Records, Scholz switched his band's recording label to MCA. The album's first track, "Amanda", was actually written in 1980 (when Boston began work on the album) and became the band's only #1 single. It reached and stayed at #1 for two weeks in November 1986. It was followed by the second Top 10 single from the album, "We're Ready", which reached #9 in 1987. The songs "Cool the Engines" and "Can'tcha Say/Still in Love" also got substantial airplay, with the "Can'tcha Say (You Believe in Me)/Still in Love" peaking at #20 in 1987 on the Billboard Hot 100. It remains Boston's last Top 40 hit to date.
Third Stage went to #1 on the Billboard 200, where it stayed for four weeks. It was the first CD-formatted album to be certified gold (500,000 copies) by the RIAA. It was also certified gold in the LP format, making it what is believed to be the first album certified in both of these formats. In all, the album was certified 4x platinum.
The album is the first Boston LP to feature electronic drum samples, the first to feature songs not written by either Scholz or Brad Delp, the first Boston LP without original members Barry Goudreau, Sib Hashian and Fran Sheehan (though Hashian and Sheehan were included in the early recording sessions and Sheehan received a writing credit). Original drummer Jim Masdea (who played on the demos that made a bulk of the first Boston album) plays drums on most of the album. This LP was also the first Boston recording to use the Scholz-invented Rockman guitar processor. No orchestral sounds or synthesizers were used on the album. Critics have noted that the album has a much darker, more somber tone than Boston's previous work.