A literature fast survey shows that the topic of strengthening concrete columns with fiber-reinforced polymer (FRP) composites has not been sufficiently covered in the available textbooks. Most of the previously published textbooks, which discussed the FRP-confined or strengthened concrete columns (see Fig. 6.1), focused on the behavior and design of circular cross-sections under concentric or eccentric axial loading. The majority of the textbooks focused on confined plain concrete columns. To the best of the author’s knowledge, none of the published textbooks sufficiently studied the available stress–strain models that describe the behavior of the FRP-confined concrete. This chapter presents the following additional contributions to the existing published textbooks about FRP composites as external reinforcements for reinforced concrete (RC) columns: (1) a comprehensive discussion on the stress–strain behavior and modeling of FRP-confined concrete circular and rectangular/square cross-columns, (2) enhancing the ductility of the RC columns using external FRP jacketing, (3) effects of exposure to short and long-term environmental conditions on the behavior of FRP composites used to strengthen the existing columns, (4) ductility design methods of FRP-confined RC columns, and (5) evaluation of the performance of FRP-confined columns considering a damage-controllable mechanical model proposed for the FRP-RC structures.