A black knee length dress is the uniform of someone who knows what she is doing. It works for the holiday party, the client dinner, the awards ceremony. The black reads as intentional and polished without trying too hard. We like versions in ponte that hold their shape through the night and crepe that drapes in a way that actually flatters. Some have interesting necklines or sleeve details that make them feel less obvious than the standard black dress. Others keep it completely clean and let the fit do the work. These are the black knee length dresses that prove the most useful piece in your closet is still the simplest one.