Her career spanned the infancy of the motion picture industry, the beginnings of Broadway, the final days of vaudeville, the transition to sound movies, the Golden Age of Radio, and the rise of television.

She made her debut as a leading lady opposite Victor McLaglen in While Paris Sleeps (1932)[6] and was cast with John Boles in his initial Fox Film venture Scotch Valley.

She played in several westerns in the early 1930s, including Fargo Express (1933)[7] with Ken Maynard and The California Trail with Buck Jones.

She may be best remembered for the 1933 movie sequel The Son of Kong, as Harold Lloyd's sister in The Milky Way (1936), and as suicidal Molly Malloy in the screwball crime comedy His Girl Friday (1940) with Cary Grant and Rosalind Russell.

[9] During that decade and the next, Mack also worked as a producer and director of radio programs, including such series as Richard Diamond, Private Detective; The Saint; and Meet Corliss Archer.

Her friend Leslie originally wanted Mack to play the title role, but they decided she was too old for the high-school-girl part when the series begain in 1941.