Cloud top heights are typically derived from passive satellite imagery by matching the estimated cloud top temperature to a vertical temperature sounding and taking the corresponding altitude as the cloud top height. Several studies have reported, however, that this method often underestimates the physical cloud top by approximately 1-2 km when compared to lidar data, even for optically thick clouds. This is mainly due to the fact that clouds often do not have sharp boundaries, and it cannot be assumed even for very thick clouds that the effective radiating center is located near the cloud top. With the advent of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, scientists now have the ability to study the vertical structure of clouds all over the globe in great detail. With 30-m vertical resolution in the lower troposphere, CALIPSO is ideal for determining cloud boundaries. This study uses high-resolution vertical profiles from CALIPSO to correct Clouds and the Earth's Radiant Energy System (CERES) cloud top heights derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. The initial correction is derived from a month of CALIPSO observations and then applied to observations from other months in order to assess the applicability of the correction to different conditions.