An investigation is carried out with an actual 13-story building to assess the viability and effectiveness of a recently proposed roof isolation system that aims at reducing the response of buildings to earthquakes. The roof isolation system entails the insertion of flexible laminated rubber bearings between a building's roof and the columns that support it, and the addition of viscous dampers connected between the roof and the rest of the building. It is based on the concept of a vibration absorber and on the idea of making the roof, flexible bearings, and viscous dampers respectively constitute the mass, spring, and dashpot of such an absorber. The investigation includes a comparison of the building's response under a severe ground motion when it is considered with and without the isolation system, as well as the determination of the properties and size of the required isolation system components. It is found that the proposed isolation system is effective, is constructable, and has the potential to become an attractive way to reduce structural and nonstructural earthquake damage in low and medium-rise buildings.