There is growing evidence from patient and neuroimaging studies that the anterior temporal lobe (ATL) should be considered a crucial part of the neural network that underpins language. Specifically, this region supports semantic representations that play a key role in various aspects of language processing. In this study, we tested the critical importance of this region for language processing in normal participants by applying repetitive transcranial magnetic stimulation over the left ATL semantic region. The ability to generate the past tense of English verbs has often been used as a test case for neurocognitive models of language. Accordingly, we used this aspect of language to investigate the impact of repetitive transcranial magnetic stimulation (rTMS) over the left ATL. As predicted by single mechanism accounts of past-tense generation, ATL rTMS had a selective impact on participants' ability to generate the past tense of irregular verbs. When combined with other evidence, these results confirm that the ATL semantic hub is a key component of the neural network for language. © The Author 2010. Published by Oxford University Press. All rights reserved.