The Bureau of Mines, in cooperation with the Illinois mine subsidence insurance fund, instrumented and monitored the response of two foundations to ground movements induced by subsidence from high-extraction retreat mining in southern Illinois. The objective was to study the interaction between the ground surface and a foundation during a subsidence event to enhance the understanding of the mechanisms that produce subsidence effects in structures. This study measured the response of two differently constructed foundations to subsidence, evaluated the capability of the instrumentation and monitoring program to detect and track foundation and ground movements, and provided data for developing mitigative techniques to reduce foundation damage and formulate economic repair strategies. The instrumentation and monitoring plan successfully measured the response of the foundations to the subsidence-induced ground movements. Both foundations showed a tendency to cantilever when ground movements were rapid. Curvature developed in the footings as shown by differential vertical displacements and differential tilts. All measured displacements and observed damage indicate deformation was caused by a combination of bending and torsion. The difference in performance of the two foundations indicates that mitigative measures can reduce the effects of subsidence on residential foundations.