World War I began in 1939, ushering in a new conservatism in fashion. Fashion designers were forced to close their houses in Paris, and “practicality” became the new buzzword in fashion, with a focus on producing sensible styles and “utility garments” which required a minimum quantity of fabric. In the United States, the L-85 Limiting Order aimed to freeze the war-time silhouette and stop rapid seasonal changes in styles in order to conserve fabric use. Tailored suits and military-influenced styles were seen in items such as belts, breast pockets, high necklines, and small collars.

The 1940s silhouette was tailored and narrow, with a nipped-in waistline and squared shoulders achieved through the use of shoulder pads. Hemlines rose to just below the knee.

Both clothing and hair were influenced by the war. For women who worked in factories, superfluous decoration and long hair posed safety threats. Hairstyles and makeup became an integral way to achieve personal style, since clothing and accessories were rationed. Hollywood stars such as Veronica Lake, Rita Hayworth, and Bette Davis were major influencers of fashion. In the light of rationed fashion, hats allowed an individual fashion statement, and small styles such as veiled pillboxes and berets, often worn at a right angle, were most popular. Shoes were usually chunky with rounded toes and featured either low-heeled or wedge soles.  Leg makeup was introduced and offered women a remedy to the rationing of nylon stockings.

American designers began developing sportswear collections, spurred by the necessity of the war-time focus on the ideals of simplicity and utility. Casual separates, shirtwaist dresses, slim skirts with patch pockets, and halter and square necklines became popular. Women could also be seen wearing trousers, although it was mainly for utilitarian purposes, not everyday wear.