This document summarizes research in 3D object categorization. It discusses approaches that use mixtures of 2D single view models, full 3D models, and multi-view models. Multi-view models link sparse interest points or object parts across views. The document also describes work by Savarese et al. that uses a probabilistic generative part-based model with canonical parts and linkage structures for 3D object detection, pose classification, and pose synthesis.