Microwave brightness temperatures were measured over a young wheat crop of varying canopy density during the First NOPEX Concentrated Field Effort near Uppsala, Sweden. Measurements were made with a portable ground-based microwave radiometer system at frequencies of 1.4 GHz and 5 GHz. The brightness temperature at each wavelength was measured at horizontal, vertical, and 45 degree polarization, and also at incidence angles ranging from nadir to 60 degrees. Four full measuring sequences were made; at full canopy, after each of two thinnings, and of the bare soil. A second series of measurements was also made over a similar plot which had been flooded with water to a depth of approximately 2 - 4 cm. Supporting data such as soil and canopy temperature, soil moisture, other soil physical properties, and canopy biomass were also collected. Preliminary results of some of the field measurements and comparisons with theoretical models are presented and discussed.