Vibrations in buildings are of increasing importance as stronger building materials and more refined and sophisticated designs result in lighter structures that are more prone to vibrations than earlier, heavier ones. This Digest presents various aspects of building vibrations and ways of avoiding or alleviating vibration-related problems. Effects of blasting, earthquake resistant design, and floor vibrations have been discussed in previous Digests and will therefore not be covered in detail here. Building vibrations fall into two categories: those that arise from internal sources and those that arise from external sources. Most vibrations generated inside buildings originate from machines (cranes, trollies, elevators, fans, pumps, drop hammers, punching presses) and from the activities of people (walking, jumping, dancing, running). Externally generated vibrations commonly arise from road and rail traffic, subways, construction activities (pile driving, blasting, excavation and compacting of soil), sonic booms, strong winds, and earthquakes. The resulting vibrations in buildings may cause annoyance to the occupants, impaired function of instruments, or structural damage.