Chicago rock mainstays Styx had been appearing on the US charts for five years by the time they released their seventh studio album. But The Grand Illusion was the one that really took them into the premier division of album rock and gave them only their second top ten pop hit in "Come Sail Away." Dennis DeYoung described the album's theme as overcoming superficial differences by recognizing "deep inside we're all the same." The album cover, created by the famed San Francisco team of Alton Kelley and Stanley Mouse, is an homage to a painting by Magritte.

"With each album this five-piece group continues to refine its act," wrote Billboard. "Grand Illusion is its most mature creation as this concept LP is an existentialist commentary on the human condition." It entered the American bestsellers on July 30, 1977 at No. 123, the first of an epic 127 weeks on the survey, by far the band's best-ever run. In September, "Come Sail Away" started its own extended Hot 100 voyage, which took it to No. 8 in the new year and helped the album to its first, gold certification the following month. By December, The Grand Illusion was platinum, and in February 1978 it offered up a second chart single in "Fooling Yourself (The Angry Young Man)," which reached No. 29.

Styx may have been named after an underworld river, but their success was now undeniably overground. In 1984, The Grand Illusion went double and triple platinum at the same time.