This article explains the Vertical Stack strategy of Ultimate Frisbee. The strategy involves having three players across the front of the field, called the Stack, and two players behind the stack, called the Sideline. The Stack is used to provide a deep threat, while the Sideline provides support and makes breaking through the Stack more difficult for the opposition. The article goes on to provide advice for how to execute the Vertical Stack, including how to set up the Stack, how to defend against it, and how to take advantage of the open spaces created by this strategy.