1979 Half-Speed Mastered Rarity. Saw cut. "Cornerstone" is the ninth studio album by the American rock band Styx, released on October 19, 1979. The album marked a significant shift in the band's musical direction, steering away from their earlier progressive rock influences to adopt a more pop-oriented sound. This transition was evident in the album’s lead single, "Babe," which became Styx's first and only U.S. number-one single. The album also featured tracks like "Why Me" and "Borrowed Time," showcasing a blend of rock and pop elements. Overall, "Cornerstone" demonstrated the band's versatility and ability to adapt to changing musical landscapes.

Commercially, "Cornerstone" was a success, reaching number 2 on the Billboard 200 chart and achieving multi-platinum status. The album's production was characterized by polished arrangements and a more radio-friendly approach, which helped broaden Styx's appeal beyond their established fan base. However, the shift in style caused some tension within the band, particularly between Dennis DeYoung and Tommy Shaw, regarding the direction of their music. Despite these internal conflicts, "Cornerstone" remains a significant entry in Styx's discography, reflecting a pivotal moment in the band's evolution and their efforts to navigate the late 1970s rock scene.