The use of glass reinforcement in concrete was conceived over thirty years ago. However, it has been within the past ten years that the advantages of glass fiber over steel for use in prestressing have become known. Past research shows that, even though the physical properties of glass fiber in the form of laminated rods are desirable for prestressing concrete, the material presents several problems. The most difficult problem is that of gripping the fiber glass rods. Other problems are creep and developing adequate design criterion. The present investigation confirms many of the previous findings with respect to gripping devices and presents data on tensile tests performed on modified commercial grips. The Fanngrip is the most promising commercial grip investigated. Post-tensioned beams are designed and tested in flexure. The recorded test data is compared with the design data to verify existing design criterion. Present design formulas provide reliable results up to tho cracking load. Deflections are calculated with sufficient accuracy by empirical equations; however, a method of finding ultimate load remains to be found. / Master of Science