To better understand the mechanics of the flat plate dilatometer expansion, a probe has been developed to measure the continuous pressure-displacement soil response during the test. This paper presents details of a specially designed Marchetti dilatometer with sensors to record the continuous displacement of the membrane, unload-reload cycles, the pore water pressure, the total pressure, and the penetration thrust. With minimal impact on the original blade design, the resulting instrumented dilatometer was tested at the University of Massachusetts-Amherst National Geotechnical Experimentation Site.