Innovative strategies driven toward improving the structural and nonstructural performance of existing buildings during large earthquakes are of paramount interest for researchers and practitioners of earthquake engineering. Likewise, strategies for enhancing performance of new structures in cost effective ways is a key issue for designers and owners. One such strategy is the use of a Nonlinear/inelastic Rooftop Tuned Mass Damper Frame (NRTMDF). This approach utilizes a rooftop penthouse structure as a tuned mass damper with mass incorporated as the roof deck of the penthouse while targeted nonlinearity and energy dissipation are introduced into the system by virtue of buckling restrained braces which link the penthouse mass to the structure below. An analytical parametric study of existing buildings, each modified with an NRTMDF demonstrates the effectiveness of this approach for reducing seismic response. The effectiveness stems from two key actions enabled by the NRTMDF. First, the NRTMDF generates elastic and transient inelastic fundamental period shifts in the structure. For most sites the result is a decrease in the seismic spectral acceleration response. Second, the NRTMDF introduces designated yielding elements within the system (buckling restrained braces). These elements serve as a channel through which seismic energy is dissipated in a safe, controlled and targeted manner. Analytical studies show that for many structures and site conditions the NRTMDF approach effectively decreases peak transient response parameters (base shear, story drift, displacement). In addition, it reduces the demand on nonstructural elements and components observed as diminished floor spectra derived from the analytical models. Energy methods demonstrate that the NRTMDF approach enables significant reductions in total energy demand on the structure in consideration of the complete response history.