Polly Ann continued to work as well, including doing "standin" for Joan Crawford, now a star. Madeup like Joan and wearing her clothes, she often posed for the billboard art that promoted the Joan Crawford movies. The casting director at MGM thought of Polly Ann when they were preparing to shoot a picture in Colorado. The leading lady would either be Dolores Costello or Joan Crawford; it was still undecided, so in the interim, Polly Ann was hired to go to Denver to do the long shots.
At the same time, Mervyn LeRoy, a gag writer for Colleen Moore at First National and who was also serving as a casting director, called Polly Ann at home. There was a 'bit part' as one of five girls in a boarding school in the Colleen Moore comedy, NAUGHTY BUT NICE. Polly Ann was caught in a dilemma: she didn't want to say no because he had given her a lot of work, but the picture in Colorado was coming up in two weeks. Gladys was standing near her while she was on the phone and she asked her mother for advice. Off handedly, Gladys suggested that he call back later and ask for Gretchen; possible she'd do. He did call back and thirteen year old Gretchen was thrilled at the invitation to go to First National for an interview, even if it would mean transferring three times on the bus to get to Burbank.
Mervyn LeRoy thought that Gretchen would do nicely for NAUGHTY BUT NICE. She would have two words to say, and since it was a silent picture, it wouldn't make any difference what her voice sounded like. But, mouthing those two words made it a "bit part" which was a step higher than a "walk on." The next day, Gretchen started work.
Gretchen continued to get bit parts in First National films and a few months later was assigned to another Colleen Moore picture, HER WILD OAT. This time she caught the star's attention, who suggested to the studio bosses that Gretchen be tested for a contract. All were elated at how well she photographed and quickly decided that she needed a more romantic sounding name than Gretchen. Colleen Moore had a renowned doll collection, and in her mind, the most beautiful of her dolls was named Loretta.