The western Nevada volcanic fi eld is the western third of a belt of calderas through Nevada and western Utah. Twenty-three calderas and their caldera-forming tuffs are reasonably well identifi ed in the western Nevada volcanic fi eld, and the presence of at least another 14 areally extensive, apparently voluminous ash-fl ow tuffs whose sources are unknown suggests a similar number of undiscovered calderas. Eruption and caldera collapse occurred between at least 34.4 and 23.3 Ma and clustered into fi ve ~0.5-2.7-Malong episodes separated by quiescent periods of ~1.4 Ma. One eruption and caldera collapse occurred at 19.5 Ma. Intermediate to silicic lavas or shallow intrusions commonly preceded caldera-forming eruptions by 1-6 Ma in any specifi c area. Caldera-related as well as other magmatism migrated from northeast Nevada to the southwest through time, probably resulting from rollback of the formerly shallow-dipping Farallon slab. Calderas are restricted to the area northeast of what was to become the Walker Lane, although intermediate and effusive magmatism continued to migrate to the southwest across the future Walker Lane. Most ash-fl ow tuffs in the western Nevada volcanic fi eld are rhyolites, with approximately equal numbers of sparsely porphyritic (≤15% phenocrysts) and abundantly porphyritic (~20-50% phenocrysts) tuffs. Both sparsely and abundantly porphyritic rhyolites commonly show compositional or petrographic evidence of zoning to trachydacites or dacites. At least four tuffs have volumes greater than 1000 km 3 , with one possibly as much as ~3000 km 3. However, the volumes of most tuffs are diffi cult to estimate, because many tuffs primarily fi lled their source calderas and/or fl owed and were deposited in paleovalleys, and thus are irregularly distributed.