In Thoroughly Modern Millie, the costumes capture the glamorous and lively spirit of the 1920s. From Millie’s stylish flapper dresses to the men’s sharp suits, each outfit reflects the era’s fashion and the characters’ personalities. The bold, period-appropriate designs, complete with accessories like cloche hats and pearls, enhance the musical’s energetic tone, celebrating the Roaring Twenties with flair and fun.