Abstract: A sign post assembly having an elongated post with a hollow end for positioning over a base member which is secured to the ground by base rod members slidably mounted in the base member and driven into the ground. A post rod member is connected to the hollow end of the post for holding the post on the base member. The post may have bowed walls and a longitudinally extending rib for increased rigidity. The base member may have a cruciform or rectangular cross section with longitudinally extending sleeves in diagonally opposite corner portions for the base rod members. The cross arm may also have a longitudinally extending rib for stiffening the arm and providing a groove for an upper sign. A tab may be provided extending outward from the hollow end of the post and have an opening through which the post rod member may be driven into the ground.