Continental extension and volcanism are generally thought to be complementary. Stratigraphic and structural data from some highly extended parts of the Basin and Range province reveal instead that rapid extension appears to have suppressed volcanism. This relation may reflect enhanced crystallization of midcrustal magmas during extension resulting from exsolution of magmatic volatiles, increased interaction of magmas with meteoric water, and dispersal of magma into smaller bodies. Some rift environments may thus be characterized by voluminous synextensional plutonism with little or no concomitant volcanism.