A physical retrieval method is described that detects cloud liquid water path (LWP) over land using polarization difference measurements from the Special Sensor Microwave Imager (SSM/I). The brightness temperature difference at 85.5 GHz is divided by the surface emissivity polarization difference to define a normalized polarization difference (NPD). The SSM/I NPD observations are compared to coincident observations of liquid water path from upward looking ground-based microwave radiometers in Oklahoma and Kansas for November and December of 1994. The comparisons reveal a moderate correlation and nonlinear relationship (which is expected from theory) between the 85.5 GHz NPD and liquid water path. The NPD method is anticipated to be valid over a broad region of the U.S., excluding the southern Mississippi Valley where the surface emissivity polarization differences are negligible. The observational results indicate that the NPD method holds promise for future routine satellite detection and retrieval of cloud LWP over land. ¿ 1998 American Geophysical Union