On 27 July 1918, Motion Picture News announced that The Testing of Mildred Vane would be actress May Allison’s second Metro Pictures Corp. production to be filmed on the West Coast. The original story was written by Charles T. Dazey who was known at the time for the play In Old Kentucky. H. L. Snyders was listed with George D. Baker as a scenario writer, but only the latter was credited in other contemporary sources.
       Filming was underway as of 17 August 1918, as reported in a Moving Picture World news item published that day which announced the casting of Darrell Foss as the leading man. Foss had also starred opposite Allison in The Return of Mary, the actress’ first picture produced at Metro studios in Hollywood. One week later, the 24 August 1918 Motion Picture News stated that the production was “making excellent progress.” Most of the interiors had already been completed, and technical director Ralph Godfrey had “erected an immense ballroom set.” A separate news item in the same edition of Motion Picture News added that principal photography was “nearing completion.”
       Although the 28 September 1918 Motion Picture News announced that the release was scheduled for 28 October 1918, the 30 November 1918 Exhibitors Herald and Motography reported that the date had changed to 2 December 1918.
       A review in the 14 December 1918 Moving Picture World by Robert C. McElravy stated: “Complete novelty of plot is a thing so rarely encountered that it brings an additional thrill when it does come along. This five-reel subject, ‘The Testing of Mildred Vane,’ cannot be given credit for entire originality, but it has a great deal of this desirable commodity and at least turns up a story of remarkable quality. There is some of the most fascinating villainy that has been shown on the screen for some time in the machinations of Dr. Hernandez, and we have seldom seen a persecuted heroine placed in a more awkward predicament than is Mildred Vane. Mildred is the daughter of Matthew Vane, or at least she is presumed to be when the story opens. But Matthew’s friend, Dr. Hernandez, a Spanish physician, once loved the girl’s mother, and is determined to have revenge upon both father and daughter because of his old disappointment in love. He persuades Matthew Vane, through some old letters, that his wife was once untrue to him and that Mildred is not in fact his daughter. The father, shocked and with his reason almost gone, leaves Mildred in the care of the doctor while he goes on a trip. While he is away the doctor discharges the family servants, makes a practical prisoner of the girl and finally tries to wed her to an unwelcome suitor. But the girl’s lover, a young professor of Greek, comes to the rescue and finally brings out the truth. This makes a compact and enjoyable feature and has few shortcomings of any sort.”
       According to the Library of Congress American Silent Feature Film Survival Database, this film is not extant.