A successful child actor, Pamelyn Ferdin appeared in various movies and television programs, including science fiction and animal shows. She also did notable work in Sunday funnies-inspired fare during the late '60s and early '70s, when her career was taking off. In 1968, after a number of guest star roles, she was cast in a sitcom based on the comic strip "Blondie", as Cookie, the Bumsteads' daughter. While the series lasted only 13 episodes, she soon got to voice Lucy Van Pelt, the know-it-all girl from the popular comic "Peanuts", in the feature film "A Boy Named Charlie Brown" and the short-format "It Was a Short Summer, Charlie Brown", both released in '69. She would voice Lucy again in a short during the early '70s, the decade in which she was most active as an actress. Most of her work was in television, but she did appear in some features, most notably "The Beguiled", an intense '71 drama starring Clint Eastwood that was intended as an antiwar statement; though initially charmed by a Yankee soldier, her character Amelia gets revenge after he kills her pet turtle. Meanwhile, her sci-fi credits included playing Lt. Laura Gantry, a novice space explorer with special mental powers, in the '77 series "Space Academy". Ferdin also brought her talent to shows featuring animals, and would later become active in the field of animal rights.