An electrical resistivity survey and accompanying soil analyses were performed over an exposed but unexcavated prehistoric house in Peoria loess in west-central Illinois. Positive resistivity anomalies occur along the trenches for the house walls and within the house, and distinctive patterns in contoured resistivity data occur over the house. Soil analyses show that quartz, kaolirite, montmorillonite, illite, and hematite are the main mineral constituents in the soil. Within the house basin, the soil is dark gray in color because of the presence of organic carbon. Prominent positive electrical resistivity anomalies occur where the dark soil is thickest.