A sleeveless midi dress reads as more formal than its sleeved counterparts and works perfectly for a graduation ceremony where you want to feel polished without being overdressed. The absence of sleeves keeps things from feeling heavy or stuffy during what is likely a warm spring or summer day. You can layer a structured blazer or a delicate shrug over it if the venue is air-conditioned or if you want added coverage. These sleeveless midi dresses work because they give you the dignity of length and formality while still keeping the whole look fresh and uncomplicated.