A comprehensive study was conducted to evaluate the efficacy of different repair and retrofit techniques for unreinforced masonry (URM) structures. The study was to identify suitable grouting materials and procedures for the repair and retrofit of URM structures, quantify the efficacy of different repair and retrofit techniques, and develop analysis tools to evaluate the performance of masonry structures before and after retrofit. To this end, a number of grouting materials and procedures were evaluated with material tests, masonry component tests and shear wall tests. The experimental results indicate that the strength and stiffness of damaged walls can be fully restored with grout injection. Furthermore, the strength and ductility of a URM wall can be greatly enhanced by the introduction of steel reinforcement.