The behavior of reinforced concrete (RC) infilled frames was investigated as a rehabilitation alternative for moderately damaged RC buildings. Five test specimens were constructed and tested. Each specimen, which consisted of two (twin) 1/3-scale, one-bay, two-story frames having the deficiencies commonly observed in residential buildings in Turkey, was tested under reverse-cyclic lateral loading until moderate damage occurred. RC infills were introduced to the damaged specimens and these infilled frames were then tested under reverse-cyclic lateral loading until failure. It was observed that both strength and stiffness were significantly improved by the introduction of the infill. The deficiency, which affected the behavior of infilled frames most adversely, was the presence of lap splices in column longitudinal reinforcement. In four of the test specimens, lap splices were made at the floor level. Lengths of the splices were much shorter than what is required in the codes. Three different local strengthening techniques were applied to the test specimens to overcome this deficiency. These local strengthening techniques prevented local failure in the spliced region of the boundary columns and improved the strength and stiffness of the infilled frame considerably. © 2004, American Concrete Institute.