The resulting show, the musical Man of La Mancha opened on Broadway in 1965 and in its original engagement ran for 2,328 performances.

Leigh followed with the show Chu Chem, which he also produced, exactly a year after Man of La Mancha, but closed on the road.

[4] His musical Home Sweet Homer, starring Yul Brynner, officially opened on Broadway in January 1976 but closed after one performance.

[6] He wrote the musical Halloween with Sidney Michaels, and although Barbara Cook and José Ferrer were in the cast, it did not reach Broadway.

[14][15] In 1977, Leigh and others at the Yale School of Music established the Keith Wilson scholarship, to be awarded "to an outstanding major in wind instrument playing."

[2] To avoid taxation for his earnings from Man of La Mancha, Leigh purchased 1,000 acres of land in Jackson Township, New Jersey over many years.

[2][17] According to The Washington Post, the commercials confused viewers, many of whom thought Leigh was running a scam or a starting a cult.