A support frame kit for canopies and display racks includes vertical posts and horizontal rails which are coupled to one another by square sockets mounted on the posts which receive square pintles projecting from the ends of the rails. In accordance with one embodiment of the invention, the rails are secured to the posts by removable pins and provide support for a canopy which is attached at its periphery to peripheral rails by attachment loops. In another embodiment of the invention rails are joined by struts and project from couplings fixed to the posts to provide shelves of a display rack.