The objective of the present study is to investigate a new energy dissipation system that combines the positive stiffness of the resetting passive stiffness damper (RPSD) with the negative stiffness of a passive negative stiffness device (PNSD). The displacement-based adjustable stiffness and energy dissipation (D-BASED) system can be designed to have independent damper stiffness and energy dissipation. Equations for modeling the RPSD and PNSD components of the D-BASED system are presented, along with an approach for designing the PNSD component. The results of laboratory experiments on a small-scale prototype D-BASED system are provided for validation of the concept. Numerical simulations are performed for the D-BASED system installed in the isolation layer of a five-story base-isolated building subject to a suite of near-field earthquake ground motions. The performance of the D-BASED system with the same net stiffness, but different levels of energy dissipation, is compared with that of the RPSD alone. It is shown that increasing the RPSD- and PNSD-component stiffness in the D-BASED system results in a reduction in the peak base drift compared to the RPSD, while limiting the building story drifts. Furthermore, it is shown that increasing the RPSD- and PNSD-component stiffness generally does not lead to an increase in the peak total force transmitted to the foundation. The D-BASED system is also found to yield smaller peak story drifts and foundation forces compared to a passive linear fluid viscous damper for a long-period base-isolated building.