ABSTRACT The Santa Catalina and Rincon Mountains north and east of Tucson, Arizona, form one of the largest core complexes on Earth. Both ranges consist primarily of Eocene leucogranites that intrude Proterozoic and late Cretaceous granitoids, and two Oligocene plutons. Mylonitic fabrics are well developed on the southern flank of the Santa Catalina Mountains and the southwestern flank of the Rincon Mountains. The corrugated form of the two ranges reflects the grooved form of the ca. 15–30 Ma Catalina–San Pedro detachment fault exposed primarily at the foot of the ranges. Normal displacement on two younger high-angle normal faults is responsible for much of the substantial relief of the ranges. This field guide is focused on fault rocks and mylonitic fabrics in the footwalls of the detachment fault and the high-angle Pirate normal fault, and includes description and analysis of shear-zone kinematics and processes, U-Pb geochronology of leucogranites, and core-complex geomorphology.