The Sun Comes Up (1949) is mainly based on the 1936 short story "A Mother in Mannville" by Marjorie Kinnan Rawlings. According to the University of South Carolina Libraries description of Rawlings' works, in 1946 MGM asked Rawlings to do a story that could star Lassie with Claude Jarman Jr.. Rawlings started with her 1936 short story "A Mother in Mannville." MGM bought the rights to Rawlings' unpublished story "A Family for Jock," re-titled it "Mountain Prelude," and sold the literary rights to The Saturday Evening Post. The story appeared The Post as a six-part serial during April 26 to May 31, 1947. But it has never been published in novel form.
The Sun Comes Up (1949) is a Metro-Goldwyn-Mayer Technicolor picture with Lassie. Jeanette MacDonald had been off the screen for five years until her return in Three Daring Daughters (1948), but The Sun Comes Up was to be her last. In it, she had to share the screen not with an up-and-coming younger actress but with a very popular animal star. MacDonald had to be under constant medication because of her severe allergy to dogs. Although her retreat from a film career can be blamed largely on an increasingly debilitating heart ailment (which eventually took her life at the age of 61 in 1965), MacDonald continued to make concert and TV appearances after this. Her last radio performance was a broadcast version of this same story on The Screen Guild Theater in March 1950.
One of the orphans is played by Tommy Rettig who, five years later, starred in the Lassie (1954) TV show.
Elizabeth Taylor, who had appeared in the first "Lassie" picture, was originally set to star in The Sun Comes Up (1949).