McCargo first entered acting as a supporting player on such popular television shows as Perry Mason (in 1964 she played murder victim Sibyll Pollard in "The Case of the Latent Lover"; and in 1965 she played defendant Louise Selff in "The Case of the Wrathful Wraith".) Her other television show appearances included: Hawaii Five-O, Hogan's Heroes, Voyage to the Bottom of the Sea, Mannix, and The Man from U.N.C.L.E..