A microwave (MW) method for deriving cloud liquid water path (LWP) and cloud water temperature (Tw) is validated by using soundings and results from a visible (VIS) and infrared (IR) retrieval method. The two retrieval methods are combined into a single technique, MVI (microwave, visible, and infrared), to estimate the frequency of multilayered clouds and the effective droplet radius re in water clouds. These techniques were applied to Meteosat and special sensor microwave/imager (SSM/I) data taken during June 1--28, 1992, over the Atlantic Stratocumulus Transition Experiment (ASTEX) region. For low clouds, as identified with the VIS-IR method, Tw on average is nearly the same as the VIS-IR cloud-top temperatures (Tc). A negative correlation between LWP and Tc was found for the clouds. For midlevel clouds, Tw is about 8 K warmer than Tc because of either large cloud thicknesses or multilayered clouds. When high clouds are found by the VIS-IR method, Tc is ~30 K colder than Tw, indicating that lower-level liquid-water clouds may be detected by the MW method. On the basis of the matched Tw and Tc observations, the estimated frequencies of multilayered high, middle, and low clouds are about 36%, 19%, and 0%, respectively, values that are similar to cloud radar measurements. Matched satellite and ground-based radar data show that the MVI technique can separate cloud layers when high ice clouds overlap lower liquid water clouds. The distributions of re for water clouds are about the same for low, middle, and broken clouds with mean and standard deviations of ~12 and 10 μm, respectively. The frequency of large droplets (re>16 μm) suggests that drizzle occurs in ~30% of the matched Meteosat-SSM/I cloudy conditions. ¿ 1998 American Geophysical Union