Harding initially desired a business career and accepted a secretarial position with the
Metropolitan Life Insurance Company. Her work included dictating letters, and upon discovering that the company's best typists would claim the best
Dictaphone recordings so they could produce the most accurate letters, Harding worked to develop tone, cadence, and diction that would produce easy to understand recordings. Her success with the Dictaphone led to work as a
script analyst, which required her to review plays and movie scripts and provide recorded oral summaries. Three years later she found her "home theater" in Rose Valley, Pennsylvania, after being directed by
Hedgerow Theatre founder Jasper Deeter in
The Master Builder. Over the years she returned to Hedgerow to reprise several of her roles. She was a prominent actress in
Pittsburgh theatre for a time, performing with the Sharp Company and later starting the Nixon Players with
Harry Bannister. In 1931, she purchased the Hedgerow Theatre building from Deeter for $5,000 and donated it to the company. In 1929, she made her film debut in
Paris Bound, opposite
Fredric March. With
talking pictures becoming the standard, producers and directors discovered that Harding's diction and pace of speech worked well with the new sound recording technology, and she soon became a leading lady. Harding's performances were often heralded by critics, who cited her stage experience for enabling her to give her characters depth. First under contract to
Pathé, which was subsequently absorbed by
RKO Pictures, Harding was promoted as the studio's 'answer' to
Metro-Goldwyn-Mayer's superstar
Norma Shearer. She co-starred with
Ronald Colman,
Laurence Olivier,
Myrna Loy,
Herbert Marshall,
Leslie Howard,
Richard Dix, and
Gary Cooper, and was often on loan to other studios, such as MGM and
Paramount. At RKO, Harding, along with
Helen Twelvetrees and
Constance Bennett, comprised a trio who specialized in the "women's pictures" genre. She soon became a leading lady; she kept in shape by using the services of
Sylvia of Hollywood. In Harding's second film,
Her Private Affair, she portrayed a wife of questionable morality, and the film was a commercial success. During this period, she was generally considered to be one of cinema's most beautiful actresses, with her waist-length blonde hair being one of her most noted physical attributes. Films during her peak include
The Animal Kingdom, Peter Ibbetson, When Ladies Meet, The Flame Within, and
Biography of a Bachelor Girl. Harding, however, eventually became stereotyped as the innocent, self-sacrificing young woman. Following lukewarm responses by both critics and the public to several of her later 1930s films, she eventually stopped making movies after she married the conductor
Werner Janssen in 1937. She returned to the big screen in 1942 to make
Eyes in the Night and to take secondary roles in other films. She played "Mary," the estranged wife of Charlie Ruggles, in the Christmas film
It Happened on Fifth Avenue in 1947. In 1956, she again starred with Fredric March in
The Man in the Gray Flannel Suit. The 1960s marked Harding's return to Broadway after an absence of decades—having last appeared in 1927. In 1962, she starred in
General Seeger, directed by and co-starring
George C. Scott, and in 1964 she appeared in
Abraham Cochrane ("her last New York stage appearance"). Both productions had brief runs, with the former play lasting a mere three performances (including previews). Harding made her final acting performance in 1965 in an episode of television's
Ben Casey before retiring. ==Personal life==