The height zi of the convective boundary layer is of primary importance for air quality studies and as a basic scaling parameter. Various instruments can measure zi. Here we present comparisons of measurements from two lidars, the High Resolution Doppler Lidar (HRDL) and the Staring/Scanning Aerosol Backscatter Lidar (SABL), and from 915-MHz lower tropospheric wind profiling radars. The lidars find zi as the top of a layer of enhanced aerosol, while the profilers find zi as an enhancement of reflectivity due to humidity and temperature gradients. Both lidars and the profilers can also measure the entrainment zone (EZ) depth. Statistical comparisons of hourly values of zi and EZ depth are presented. Examples of good and poor agreement are explored to determine the strengths and weaknesses of each instrument. High time resolution (a few to 30 second) data are also shown and compared