Boundary layer stratocumulus clouds play an important role in the Earth’s radiative budget and climate. This paper uses reflectivity data from the Millimeter-Wave Cloud Radar (MMCR) at the Southern Great Plains (SGP) Atmospheric Radiation Measurement Climate Research Facility (ACRF) to explore variability of continental boundary layer stratocumulus. Neglecting subgrid variability in numerical models can lead to biases in radiative heating and microphysical process rates. Analysis of over 70 hours of radar data demonstrates that cloud system variability increases with mean reflectivity, indicating that drizzling clouds are more variable than nondrizzling clouds. Variability is highly vertically dependent, suggesting that numerical model accuracy may improve if this vertical dependency is included in subgrid cloud parameterizations.