The Truth About Youth is DM's second of his five films with Loretta Young. Based on Henry V. Esmond's play, "When We Were Twenty-One," it had two prior film treatments, both silent, made in 1915 and 1920. Early film pioneer Edwin S. Porter co-directed (with Hugh Ford) the first version.
 
Dick Carewe (Conway Tearle) has pledged to care for the young son of his late friend Charles Dane. Richard "the Imp" Dane (DM) is celebrating his twenty-first birthday in a wild way, and staying out on the town, misses his surprise party. Dick's plans for "the Imp" include marriage to Phyllis Ericson, (Loretta Young) the housekeeper's lovely daughter. "The Imp" however, has plans of his own and becomes involved with Kara "the Firefly," (Myrna Loy) a nightclub dancer and notorious breaker of young men's hearts. Thinking him wealthy, Kara marries Imp only to toss him out as soon as she realizes he can't pay her voluminous bills. All the while, Phyllis is secretly in love with Dick, in part due to his selfless devotion to "the Imp." Not realizing the vows have already been taken, Dick tries to convince Imp of his folly. After learning the truth he still covers for Imp and assures him he can yet have a happy life with Phyllis. However, Phyllis finally makes known her love for Dick and they embrace in the final scene.
 
The Truth About Youth is an enjoyable picture. Mixing comedy, drama, and romance, it keeps a steady pace and illuminates male-female relationship expectations of the period. DM captures the essence of his character well and has a great scene when he, returning from his birthday night out, arrives at home "blotto."