Many existing buildings and structures often require to be retrofitted due to lack of capacity to resist the applied actions. This chapter discusses various reasons why structures may require retrofitting and focuses on various techniques for the retrofitting of cross-sections to improve their capacity. Enhancement of capacity for axial loads, bending moments, shear and torsion is discussed separately. Several typical techniques and materials for retrofitting of cross-sections of reinforced concrete beams, columns and slabs, etc., are presented. A brief discussion of various informative references related to the evaluation and retrofitting of structures is included for practical applications. The methods to calculate the capacity of retrofitted cross-sections using the formulations presented in Chapters 2–4 are presented. A detailed discussion of evaluation of sections subjected to high temperatures is also discussed.