A cocktail dress is a dress suitable at semi-formal occasions, sometimes called cocktail parties, usually in the late afternoon, and usually with accessories.

After World War I, the idea of the "working woman" became popular. After 1929, it was more common to see women in a social context. With the help of liberation organizations, the idea of a "modern woman" began to rise, and soon the "drinking woman" could be seen in business settings. Companies increasingly hosted cocktail parties to have an entertaining environment for employees and customers to mingle. These parties usually began after 5:00 P.M. Since guests are expected to walk around and meet people, clothes made for these occasions are often functional and comfortable. This practical and fashionable garment became a popular uniform for progressive elite women in the 1920s.