She appeared in professional theatre in productions of “The Mystery of Edwin Drood,” “Singin’ in the Rain,” “The Threepenny Opera,” “Jesus Christ Superstar,” “Evita,” and “Cabaret,” among others. She received Irene Ryan Nominations for her roles as Lizzie in “Baby” and Trina in “Falsettos.” Jeffreys performed in numerous other educational theatre presentations, including “The Man Who Came to Dinner,” “A Little Night Music,” “While the Sun Shines,” and “A Funny Thing Happened on the Way to the Forum.” She also appeared in several cabaret productions.

Jeffreys has received further performance training in: voice with Steven Chicurel and Susan Durham Lozaw; acting with Be Boyd and JJ Rusculla; and dance with Brian Vernon and Gary Flannery.

Her list of secondary skills includes introductory stage combat; Standard British (Received Pronunciation), Cocney, Southern, and Brooklyn dialects; violin; and piano.