Small animal PET is increasingly utilized to assess efficacy of therapeutic interventions; and in parallel, to validate the use of current and novel imaging agents and targets for translation to the clinic. One of the many advantages of PET imaging is that it offers quantifiable measures of the underlying biology. With that in mind, we review kinetic modeling in quantifying small animal PET images. The review provides a primer on PET image quantification followed by a brief discussion on factors that may affect PET image quantification. We will conclude with application of quantitative imaging in metabolic imaging and delve into advanced topics on voxel-by-voxel kinetic modeling.