Billy Sherrill, a country music record producer and songwriter who helped create the smooth “countrypolitan” sound of the 1960s and ‘70s, died Aug. 4 in Nashville. He was 78.

His son-in-law, George Lale, confirmed the death. The cause was not disclosed.

Mr. Sherrill helped such performers as Tammy Wynette, George Jones and Charlie Rich become crossover stars, and produced such hits as “Stand By Your Man” (1968), which he co-wrote with Wynette.

Other hit songs he produced included Rich’s “The Most Beautiful Girl” and “Behind Closed Doors” (both 1973) and Jones’s “He Stopped Loving Her Today” (1980).

Mr. Sherrill’s production style incorporated overdubbing, strings and background vocals into country music to encourage crossover success.

Mr. Sherrill was born Nov. 5, 1936, in Phil Campbell, Ala. His father was an evangelical preacher.

Mr. Sherrill played piano and sang in his childhood. He began working for the CBS record label in 1964. He won a Grammy Award for co-writing “Almost Persuaded,” in 1966. The song was a No. 1 hit for David Houston.

Mr. Sherrill was instrumental in signing Wynette, Barbara Mandrell and Janie Fricke to record deals. He also worked with Ronnie Milsap, Johnny Paycheck, Elvis Costello and Ray Charles.

Country music producer and songwriter Billy Sherrill in 2012. (Rick Diamond/Getty Images for ACM)