Optical Projection Tomography (OPT) is an imaging technique, which has proven to be ideally suited to the observation and quantification of kidney development in rodents. Unlike confocal microscopy systems, OPT is capable of imaging the organ in toto across a long window of embryonic development at sufficient resolution to capture relative changes in branching dynamics, pelvis development, and nephrogenesis. Here, we describe how to image kidneys by OPT, and initial steps to quantify kidney development from this data.