Alfred Gerald Caplin was born in New Haven, Connecticut in 1909. He was the oldest child of a Jewish family. When Al was 9 years old, he lost one of his legs in an accident. He spent 5 year in High School, and often would joke that he "failed Geometry 9 times". He was hired by Ham Fisher as an assistaint on his comic strip, "Joe Palooka", eventually his work on that strip lead to the creation of "Lil Abner" in 1934, which was soon an instant success. During World War II, Capp would visit hospitals and entertain soldiers, who had lost limbs in battle. Being an amputee himself, he would try to encourage them to live life despite their afflictions. By the 1960s, Capp became a Conservative and gained notoriety for criticizing the young Liberal movement and members of it, including Ted Kennedy, John Lennon, Yoko Ono, and many others.
His brother, Eliot Caplin was also a cartoonist. Many assistants helped him on Lil' Abner, over the years, including Frank Frazetta.
Capp also wrote the comic strip Abbie an' Slats with others doing all the art.