This report summarizes important parts of the history of Cenozoic sedimentation and sedimentary rocks throughout Arizona. It is an expanded version of the report that appears in AGS Digest 15. In particular, the section on the Gila Group is expanded, and sections on Pleistocene glaciation, river integration, and basin dissection are included. A more detailed reference list documents more fully previous work. In this summary, the physiographic provinces of the State shown in Figure 1 will be used. 'The Colorado Plateau province is bounded on the southwest by the Mogollon Rim, as shown, and on the west by the Grand wash cliffs. The remainder of Arizona shall be called the Basin and Range province, or "southern Arizona." The transition zone is a region separating the Colorado Plateau and the well-defined Basin and Range country, with intermediate structural and physiographic characteristics.