Dome-shaped space trusses can be derived from a flat configuration by means of posttensioning. The structure considered here is devised to be a near mechanism initially and during the posttensioning operation. It is a near mechanism as only the flexural stiffness of the continuous top chords provides any resistance to deformation. Therefore, no appreciable force is induced in the members of the structure during the shape formation process. The results of experimental and theoretical work on the shape formation of a dome-shaped space truss by means of posttensioning are presented herein. An analytical procedure that includes both geometric and material nonlinearities is developed to determine the final shape of the dome-shaped space truss, using commercially available finite-element software. The ultimate aim is to lead to significant economies in the construction of large-span lightweight structures by eliminating or minimizing the need for scaffolding and heavy cranes in the shaping and erection of such structures.