Marshall wrote her first song in 1973 at age 24. "I was a late bloomer. I've always been a late bloomer. In fact, I probably won't completely bloom until I take my last breath at hopefully age ninety-five-or-six!" Since then, Marshall has written over two hundred songs.
Her "Betty's Bein' Bad" was awarded a BMI citation (1987) for airplay and was a finalist for "Country/Rock Song of the Year" at the Music City News National Songwriter Awards Show. "Betty" is now a member of BMI's "Million-Air" elite, having logged over a million performances worldwide. Marshall's "X-ray Eyes" (co-written with friend Diana Haig) won honorable mention in the 1989 Music City Song Festival in the Rock/R&B/Soul Category.