Excessive vibration is one of the main reasons leading to partial damage and in some cases collapse of tall buildings and structures. Impact dampers provide an effective, economical, and easy to install solution to the vibration problem in several applications. The latest developed type in the impact dampers family is the Linear Particle Chain (LPC) impact damper. It consists of a linear arrangement of two sizes of freely moving masses, constrained by two stops. This paper presents the results of an experimental investigation on the effectiveness of the LPC impact damper in damping the vibrations of a multidegree- of-freedom system under different types of excitations. A prototype of the LPC impact dampers is fabricated and tested in our lab using a three-story frame structure. The experimental outcomes clearly show that the LPC impact damper can effectively attenuate the free and forced vibrations of flexible structures.