You can get your Yale ID when you arrive on campus. To get your ID go to the Yale ID center which is located at 57 Lock Street, 1st Floor (behind the Yale Health building). You will need your Yale NetID and a government issued photo ID.
From the Sterling Law Building go out through the Grove Street door and make a left on to Grove Street. Take a right on Ashmun Street and right on Lock Street. The ID Center is located between the Yale Police Department and Yale Health.