Coghlan was born in New Haven, Connecticut, on March 15, 1916. He moved to California with his family as a child and became an extra in silent films along with his mother and father. After several years of appearing in small roles he was signed to a contract under Cecil B. DeMille in 1925 and appeared in numerous silents over the next decade. Coghlan made the transition to talkie films in 1930 and was featured as a young James Cagney in Public Enemy (1931). He also starred as Sam Williams, with Leon Janney as Penrod, in 1931’s Penrod and Sam.
He continued his career