This case study presents an investigation of disturbing noises emanating from the curtain wall system of a multi-story office building located in the southeastern United States. Shortly after the initial construction of the building, building occupants complained of loud popping noises emanating from the exterior building facade. These noises were of a frequency and magnitude to negatively influence the work environment in adjacent office space. The cause of the noises was investigated by several groups with conflicting results. At the request of the building's general contractor, an investigation was undertaken to determine the cause of the disturbing noises and to develop remedial recommendations. This investigation included a detailed review of the curtain wall shop drawings and on-site observations to identify questionable details possibly responsible for the noises. The most probable cause of the noises was identified as diurnal solar gain that produced unaccommodated movements in the curtain wall system. The orientation and curvature of the wall combined to allow a thermal expansion that progressed along the wall. The details of the curtain wall construction restrained the movement, leading to sudden release of confining stress. To confirm this hypothesis, affected areas of the curtain wall were instrumented with accelerometers and deflection gages strategically located to pinpoint the origin of the noises. To further confirm the point-of-origin identified by the accelerometers, a series of exploratory openings were made to review curtain wall details. After the source of the noise was positively identified, remedial recommendations to mitigate the disturbance were implemented by the building owner.