The Oligocene-Miocene Questa caldera and related rocks of the Lati volcanic field are exposed along the eastern flank of the Rio Grande rift in northern New Mexico. These rocks bracket in age the beginning of extensional tectonics in the region approximately 25--26 m.y. ago. The early phase of extension is characterized by currently low-angle normal faults that caused steep tilting of volcanogenic units, particularly within the Questa caldera. Paleomagnetic measurements on intrusive and extrusive rocks from the Latir field show that tilting began abruptly after the eruption of the Amalia Tuff and subsequent formation of the Questa caldera 26 m.y. ago. Specifically, most of the tilting occurred after the intracaldera welded tuff and uppermost portion of the subcaldera magma chamber had cooled and become magnetized, but before the subsequent resurgent plutons had been emplaced and cooled sufficiently to also become magnetized about 1 m.y. later. Differential uplift of the region exposes similarly aged subvolcanic plutonic rocks to the south that also have untilted magnetizations. Tilting had ceased altogether by the time the late-stage plutons were magnetized, at least within the caldera structure and to the south. Younger rift-related sedimentary rocks and interbedded basalt flows (15 m.y. old) show that tilting continued to the north of the caldera past this time. However, paleomagnetic evidence indicates that a nearby 7- to 11-m.y.-old rhyolite dome is probably untilted, suggesting that significant tilting in the region had ended by this time. The latest phase of extension is characterized by high-angle deeply penetrating normal faults, which are responsible for the high structural relief presently observed in the region.