Individuals show marked variation in their responses to threat. Such individual differences in “behavioral inhibition” (BI) play a profound role in mental and physical wellbeing. BI is thought to reflect variation in the sensitivity of a distributed neural system responsible for generating anxiety and organizing defensive responses in response to threat and punishment. Although progress has been made in identifying the key constituents of this behavioral inhibition system (BIS) in humans, the involvement of dorsolateral prefrontal cortex (dlPFC) remains unclear. Here, we acquired self-reported BIS-sensitivity and high-density EEG from a large sample (n=51). Using the enhanced spatial resolution afforded by source modeling techniques, we show that individuals with greater tonic activity in right posterior dlPFC rate themselves as more behaviorally inhibited. This observation provides novel support for recent conceptualizations of BI and clues to the mechanisms that might underlie variation in threat-induced negative affect.