She began her career in acting during the 1960s, notably in a recurring role as Sarah Johnson, a secretary in the television series The Man from U.N.C.L.E., 1965.
[1] She focused on writing for action-adventure films, an unusual genre for women scriptwriters in Hollywood during the 1970s.
[1] The Hollywood Reporter called Chapman "a pioneering female screenwriter in the action-adventure genre.
[1][4] She married right out of college, and her husband wanted to be an actor, so they moved to Los Angeles during the early 1960s.
[2] Agents at the William Morris Agency suggested her secretarial position led to her early acting roles.
She then was signed to write three features for writer-producer Norman Maurer’s unit at Columbia, 20,000 Bikinis Under the Sea, That Loving Feeling and It’s a Tuf Life, but the beach party fad ended before any were produced.
[4][9][10] She alternated between acting and writing, having a semiregular role on The Man from U.N.C.L.E., playing the secretary of Napoleon Solo.
[4] She helped write the pilot Where the Girls Are (1968), and appeared in Land's End, with Desi Arnaz, an experience she hated so much it made her decide to quit acting.
She did the unproduced feature Occam’s Razor (1969) for a company she formed with Harley Hatcher: Har-Leigh.
[4] She was hired to rewrite the script for Pursuit which became Dirty Mary Crazy Larry (1974), a huge success.
[4] She sold Detroit Boogie (1974), a spec script, to Dino De Laurentiis, and did the prison film The Tin Walls (1975) for Robert Ellis Miller.
I couldn’t write a romantic comedy or a chick flick or a love story if my life [depended on it].
"[4] Chapman wrote some scripts in the late 1970s — The Laconia Incident (1977), Felonious Laughter (1978), Rhintestone Heights and Motordrome Project (1980) — that were not filmed.
[4] Chapman wrote the pilot for Walker, Texas Ranger (1993) but had an unhappy experience and left the show after only writing a few episodes.