‘Cocktail attire’ is menswear's most confusing dress code. What is cocktail attire? The cocktail attire dress code first appeared in the 1920s and 1930s, when cocktail parties became fashionable pre-dinner affairs for fancy people. Let's get the biggest question out of the way first: yes, cocktail attire almost always means a suit – but context matters. Cocktail attire also does not mean any form of the black tie dress code, either, and so white dinner jackets are not correct.”