At age 6, Megna made his acting debut in Frank Loesser's Broadway musical "Greenwillow". At 7, he starred in "All the Way Home", an adaptation of James Agee's novel about the effect of a father's death on his family. This led to his being cast as Charles Baker "Dill" Harris, the toothy young summer visitor in the 1962 film "To Kill a Mockingbird". The character was based on writer Truman Capote, a childhood friend and later associate of Harper Lee, the author of the original novel.