Comparisons between the latest version of the VIIRS cloud mask (VCM) algorithm in the PEATE (Product Evaluation and Analysis Tool Element) system, the Collection 5 MODIS cloud mask (MOD35), a modified form of MOD35 where only those spectral bands available to VIIRS are used, and indications of cloud from CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) are performed and reported. While the VCM in the PEATE does not necessarily represent the very latest version of the algorithm due to transition time from science to operational code, this work will help identify effects due to differences in spectral coverage provided by the MODIS vs. VIIRS instruments, as well as provide a comparison of algorithms. Both VCM and MOD35 results will be created using Aqua MODIS radiance and geolocation input data and identical ancillary data. Cloud data from the active sensor CALIPSO will be used to indicate overall quality, as well as regions and/or scene types where one or both imager algorithms display increased uncertainty. The PEATE system at the University of Wisconsin-Madison will be used to produce monthly average results from the four mid-latitude seasons, where CALIPSO and MODIS instantaneous observations are collocated in time and space.