Full-scale lateral load tests were conducted on twelve rigid piers constructed at the Iowa State University Spangler Geotechnical Experimentation Site (SGES) to evaluate the scale and base shear effects. The soil is glacial till with average undrained shear strength of 59 kPa from ground surface to 3 m deep. Results show that the load-displacement behavior of all piers at the SGES can be described by the simple power function: s/s[subscript f]=(Q/Q[subscript ult])2·39. Also, a parametric study shows that the exponent of the power function ranges from 1.7 to 3, which depends on the undrained shear strength and e50 of the soil. The base shear effect becomes insignificant when the pier slenderness ratio (L/D) is about seven. Load displacement behavior of the pier can be well predicted by consolidated undrained (CU) triaxial test.