A hybrid passive control device (HPCD) consisting of a high-damping rubber (HDR) damper in series with a buckling-restrained brace (BRB) provides an innovative two-phase system for improving structural response to earthquakes. The initial phase provides damping for all magnitudes of vibration through an HDR damper. The second phase is initiated by a locking mechanism in the damper. Once engaged, the mechanism transfers sufficient force to yield the BRB. Component testing of an HPCD prototype was used to demonstrate performance and validate device design. The experimental results reported in this paper show the expected phased behavior and energy dissipation. The physical testing provides a proof-of-concept for the HPCD and supplies the motivation for further development.